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You searched for: Publication Year 2017 Remove constraint Publication Year: 2017 Subject term chemical structure Remove constraint Subject term: chemical structure
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1. (+)- and (−)-Ecarlottones, Uncommon Chalconoids from Fissistigma latifolium with Pro-Apoptotic Activity

Author:
Charlotte Gény; Alma Abou Samra; Pascal Retailleau; Bogdan I. Iorga; Hristo Nedev; Khalijah Awang; Fanny Roussi; Marc Litaudon; Vincent Dumontet
Source:
Journal of natural products 2017 v.80 no.12 pp. 3179-3185
ISSN:
1520-6025
Subject:
apoptosis; bark; chemical structure; nuclear magnetic resonance spectroscopy; spectral analysis
Abstract:
... Four new compounds, (+)- and (−)-ecarlottone (1), (±)-fislatifolione (5), (±)-isofislatifolione (6), and (±)-fislatifolic acid (7), and the known desmethoxyyangonin (2), didymocarpin-A (3), and dehydrodidymocarpin-A (4) were isolated from the stem bark of Fissistigma latifolium, by means of bioassay-guided purification using an in vitro affinity displacement assay based on the modulation of Bcl-xL ...
DOI:
10.1021/acs.jnatprod.7b00494

2. (+)-Thalianatriene and (−)-Retigeranin B Catalyzed by Sesterterpene Synthases from Arabidopsis thaliana

Author:
Shao Jie; Chen Qing-Wen; Lv Hua-Jun; He Juan; Liu Zhi-Feng; Lu Yan-Na; Liu Hai-Li; Wang Guo-Dong; Wang Yong
Source:
Organic letters 2017 v.19 no.7 pp. 1816-1819
ISSN:
1523-7052
Subject:
Arabidopsis thaliana; X-ray diffraction; biosynthesis; chemical structure; derivatization; genes; nuclear magnetic resonance spectroscopy; organic compounds
Abstract:
... Two GFPPS linked (+)-thalianatriene (1) and (−)-retigeranin B (2) sesterterpene synthase genes were identified from the genome of Arabidopsis thaliana. 1 possesses an unprecedented 11–6–5 tricyclic ring system, while 2 contains a characteristic 5–5–5–6–5 pentacyclic ring system. Their structures were determined by extensive NMR spectroscopy, chemical derivatization, and X-ray crystallography. The ...
DOI:
10.1021/acs.orglett.7b00586

3. (2+1)-Cycloaddition Reactions Give Further Evidence of the Nitrenium-like Character of 1-Aza-2-azoniaallene Salts

Author:
Al-Bataineh Nezar; Houk K. N.; Brewer Matthias; Hong Xin
Source:
Journal of organic chemistry 2017 v.82 no.7 pp. 4001-4005
ISSN:
1520-6904
Subject:
alkenes; chemical reactions; chemical structure; organic chemistry; salts
Abstract:
... Cationic 1-aza-2-azoniaallene salts react with structurally constrained alkenes in intramolecular reactions by C–H insertion at the allylic position, or by (2+1)-cycloaddition with the alkene followed by ring opening. The latter reaction gives further evidence of the nitrenium-like character of 1-aza-2-azoniaallene salts. DFT calculations show that alkene addition is intrinsically more favorable, ...
DOI:
10.1021/acs.joc.7b00407

4. (2S,4R)-Hyp-(S)-Phe-OMe dipeptide supported on imidazolium tagged molecules as recoverable organocatalysts for asymmetric aldol reactions using water as reaction medium

Author:
Arturo Obregón-Zúñiga; Eusebio Juaristi
Source:
Tetrahedron 2017 v.73 pp. 5373-5380
ISSN:
0040-4020
Subject:
catalysts; chemical elements; chemical reactions; chemical structure; organic compounds; solvents; stereochemistry
Abstract:
... Four novel chiral imidazolium tagged molecules derived from dipeptide (2S,4R)-Hyp-(S)-Phe-OMe were prepared and evaluated as organocatalysts in the asymmetric aldol reaction using water as solvent. It was found that catalysts incorporating the hexanoyl linker are active down to 5 mol% and afford aldol products with up to 94% yield, up to 98:2 dr and up to 97:3 er. This chiral imidazolium catalyst ...
DOI:
10.1016/j.tet.2017.07.037

5. (3 + 2)-Annulation of p-Quinamine and Aryne: A Strategy To Construct the Multisubstituted Hydrocarbazoles

Author:
Xu Dengyu; Zhao Yulong; Song Dengpeng; Zhong Zhuliang; Feng Shangbiao; Xie Xingang; Wang Xiaolei; She Xuegong
Source:
Organic letters 2017 v.19 no.13 pp. 3600-3603
ISSN:
1523-7052
Subject:
carbon; chemical reactions; chemical structure; organic compounds
Abstract:
... A strategy for the synthesis of multisubstituted hydrocarbazoles has been developed through (3 + 2)-annulation of p-quinamines and arynes. In this way, new analogs of hydrocarbazoles with quaternary carbon center can be synthesized in satisfactory yield under mild conditions. Furthermore, this (3 + 2)-annulation can be easily scaled-up, and the products can be modified through simple transformatio ...
DOI:
10.1021/acs.orglett.7b01578

6. (Diacetoxy)iodobenzene-Mediated Oxidative C–H Amination of Imidazopyridines at Ambient Temperature

Author:
Mondal Susmita; Samanta Sadhanendu; Jana Sourav; Hajra Alakananda
Source:
Journal of organic chemistry 2017 v.82 no.8 pp. 4504-4510
ISSN:
1520-6904
Subject:
ambient temperature; amination; chemical structure; indolizines; organic chemistry; regioselectivity
Abstract:
... (Diacetoxy)iodobenzene (PIDA)-mediated direct oxidative C–H amination for the synthesis of 3-amino substituted imidazopyridines has been achieved under metal-free conditions at room temperature in short reaction times. This methodology is also applicable for the regioselective amination of indolizines. Experimental results suggest that the reaction likely proceeds through a radical pathway. ...
DOI:
10.1021/acs.joc.7b00564

7. (Oligo-)Thiophene Functionalized Tetraazaperopyrenes: Donor–Acceptor Dyes and Ambipolar Organic Semiconductors

Author:
Hahn Lena; Hermannsdorfer André; Günther Benjamin; Wesp Tobias; Bühler Bastian; Zschieschang Ute; Wadepohl Hubert; Klauk Hagen; Gade Lutz H.
Source:
Journal of organic chemistry 2017 v.82 no.23 pp. 12492-12502
ISSN:
1520-6904
Subject:
X-ray diffraction; chemical reactions; chemical structure; dyes; electrochemistry; fluorescence emission spectroscopy; organic chemistry; terthiophenes; thiophene; transistors; ultraviolet-visible spectroscopy
Abstract:
... Tetraazaperopyrenes (TAPPs) have been functionalized with thiophene and terthiophene units of different architecture resulting in a variety of organic donor–acceptor (D–A) compounds. The influence of the connection of the thiophenes to the TAPP core on their structural, photophysical and electrochemical properties has been studied in detail by a combination of X-ray crystallography, UV–vis and flu ...
DOI:
10.1021/acs.joc.7b02286

8. (Propargylsulfanyl)-2-aza-1,3,5-trienes as a direct source for novel family of highly functionalized 4,5-dihydro-1,3-thiazoles

Author:
Nina A. Nedolya; Ol'ga A. Tarasova; Alexander I. Albanov; Lyudmila V. Klyba; Boris A. Trofimov
Source:
Tetrahedron 2017 pp. -
ISSN:
0040-4020
Subject:
chemical reactions; chemical structure; dimethyl sulfoxide; isothiocyanates
Abstract:
... A novel, simple approach to 2-(1-alkoxyprop-1-enyl)-5-ethenylidene-4,5-dihydro-1,3-thiazoles has been disclosed through the reaction of (propargylsulfanyl)-2-aza-1,3,5-trienes (readily available from alkoxyallenes, isothiocyanates, and propargyl bromide) with potassium or sodium tert-butoxide (1.1–1.4 equiv) under mild conditions [DMSO/THF (∼1:4–5), ca. −30 °C, 15–30 min]. The process proceeds thr ...
DOI:
10.1016/j.tet.2016.12.064

9. (Z)-Selective Hydrosilylation of Terminal Alkynes with HSiMe(OSiMe3)2 Catalyzed by a Ruthenium Complex Containing an N-Heterocyclic Carbene

Author:
Yuichiro Mutoh; Yusei Mohara; Shinichi Saito
Source:
Organic letters 2017 v.19 no.19 pp. 5204-5207
ISSN:
1523-7052
Subject:
alkynes; antineoplastic agents; bioactive compounds; carbenes; catalytic activity; chemical structure; derivatization; heterocyclic nitrogen compounds; ruthenium
Abstract:
... The N-heterocyclic-carbene-ligated ruthenium complex [RuHCl(CO)(H₂IMes)(PCy₃)] exhibits high catalytic activity for the (Z)-selective hydrosilylation of various terminal alkynes with 1,1,1,3,5,5,5-heptamethyltrisiloxane (HSiMe(OSiMe₃)₂). The stereoretentive derivatization of the (Z)-alkenylsiloxanes allows the synthesis of biologically active compounds, e.g. potent antitumor agents and inhibitors ...
DOI:
10.1021/acs.orglett.7b02477

10. A (salicylaldiminato)Pt(II) complex with dimethylpropylene linkage: Synthesis, structural characterization and antineoplastic activity

Author:
Mohammad Azam; Saud I. Al-Resayes; Saied M. Soliman; Agata Trzesowska-Kruszynska; Rafal Kruszynski; Zahid Khan
Source:
Journal of photochemistry and photobiology 2017 v.176 pp. 150-156
ISSN:
1011-1344
Subject:
ambient temperature; antineoplastic activity; cell proliferation; cell viability; chemical structure; colorectal neoplasms; dimethyl sulfoxide; ethanol; humans; ligands; monitoring; nuclear magnetic resonance spectroscopy; solvents
Abstract:
... A novel (salicylaldiminato)Pt(II) complex with two different molecular structures, one solventless ((salicylaldiminato)Pt(II)) 1 and another one solvated ((salicylaldiminato)Pt(II). C2H5OH), 1·C2H5OH, has been obtained by the reaction of a salen ligand with [PtCl2(DMSO)2] in ethanol at room temperature. The asymmetric unit of solventless 1 contains 9 such complex molecules whereas 1·C2H5OH contain ...
DOI:
10.1016/j.jphotobiol.2017.10.005

11. (±)-Rubioncolin D, a pair of enantiomeric naphthohydroquinone dimers from Rubia oncotricha

Author:
Si-Meng Zhao; Zhe Wang; Xiao-Qiang Chen; Mao-Bo Huang; Ning-Hua Tan
Source:
Tetrahedron letters 2017 pp. -
ISSN:
0040-4039
Subject:
Rubia; carbon; chemical reactions; chemical structure; chromatography; circular dichroism spectroscopy; cytotoxicity; neoplasms; organic compounds; spectral analysis; stereochemistry
Abstract:
... A pair of novel enantiomeric naphthohydroquinone dimers with an unprecedented spiro[4.5] carbon core, (±)-rubioncolin D (1), were isolated from Rubia oncotricha. The racemic mixture of 1 was separated by chiral column chromatography. Their structures and stereochemistry were elucidated by extensive spectroscopic analysis and electronic circular dichroism calculation. Both compounds (+)-1 and (-)-1 ...
DOI:
10.1016/j.tetlet.2017.06.063

12. (π-Allyl)palladium coupling of 2-(tributylstannyl)cyclopent-2-enone for the synthesis of jasmonoid analogs

Author:
Florencia Parpal; Enrique Pandolfi; Viviana Heguaburu
Source:
Tetrahedron letters 2017 v.58 pp. 1965-1968
ISSN:
0040-4039
Subject:
Lewis acids; chemical structure; geometry; isomerization; jasmonic acid; olefin; palladium; pest resistance; plant development
Abstract:
... The coupling of 2-(tributylstannyl)cyclopent-2-enone with several (π-allyl)palladium complexes derived from allylic electrophiles was investigated as the key step in the synthesis of jasmonoids. These compounds have an important role in plant development, triggering direct and indirect responses when harmed to induce pest resistance. Palladium-catalyzed coupling conditions to obtain a jasmonoid li ...
DOI:
10.1016/j.tetlet.2017.04.018

13. (−)-Pseudodistomin E: First Asymmetric Synthesis and Absolute Configuration Assignment

Author:
Davies Stephen G.; Fletcher Ai M.; Roberts Paul M.; Thomson James E.; Zimmer David
Source:
Organic letters 2017 v.19 no.7 pp. 1638-1641
ISSN:
1523-7052
Subject:
chemical reactions; chemical structure; iodides; lithium; nitrogen; organic compounds
Abstract:
... (−)-Pseudodistomin E has been prepared for the first time, allowing its structure and absolute configuration to be confirmed. The established conjugate addition of lithium (S)-N-allyl-N-(α-methyl-p-methoxybenzyl)amide to methyl (E,E)-hepta-2,5-dienoate generated the C(2)-stereocenter, and iodolactonisation of a derivative generated the remaining two stereogenic centers. Ensuing iodide displacement ...
DOI:
10.1021/acs.orglett.7b00434

14. 1,3-Dipolar Cycloaddition Reactions of Low-Valent Rhodium and Iridium Complexes with Arylnitrile N-Oxides

Author:
Ugur Ilke; Agopcan Cinar Sesil; Dedeoglu Burcu; Aviyente Viktorya; Hawthorne M. Frederick; Liu Peng; Liu Fang; Houk K. N.; Jiménez-Osés Gonzalo
Source:
Journal of organic chemistry 2017 v.82 no.10 pp. 5096-5101
ISSN:
1520-6904
Subject:
chemical structure; cycloaddition reactions; energy; iridium; ligands; methodology; organic chemistry; organic compounds; oxidation; oxides; rhodium
Abstract:
... The reactions between low-valent Rh(I) and Ir(I) metal–carbonyl complexes and arylnitrile oxides possess the electronic and structural features of 1,3-dipolar cycloadditions. Density functional theory (DFT) calculations on these reactions, involving both cyclopentadienyl and carboranyl ligands on the metal carbonyl, explain the ease of the chemical processes and the stabilities of the resulting me ...
DOI:
10.1021/acs.joc.7b00282
PubMed:
28414468
PubMed Central:
PMC5679111

15. 1,3-Dipolar Cycloaddition of Nitrile Imine with Carbon Dioxide: Access to 1,3,4-Oxadiazole-2(3H)-ones

Author:
Guo Chun-Xiao; Zhang Wen-Zhen; Zhang Ning; Lu Xiao-Bing
Source:
Journal of organic chemistry 2017 v.82 no.14 pp. 7637-7642
ISSN:
1520-6904
Subject:
carbon dioxide; chemical reactions; chemical structure; imines; organic chemistry; oxadiazon
Abstract:
... Efficient synthesis of 1,3,4-oxadiazole-2(3H)-one was achieved by CsF/18-crown-6 mediated 1,3-dipolar cycloaddition of nitrile imine and 2.0 MPa of CO₂. CsF/18-crown-6 played a key role in enhancing the reactivity of CO₂ as a 1,3-dipolarophile. The practical utility of this transition-metal-free approach to 1,3,4-oxadiazole-2(3H)-one is highlighted by the convenient synthesis of a commercial herbi ...
DOI:
10.1021/acs.joc.7b00963

16. 1,3-Dipolar cycloaddition of uracil derivatives with nitrile oxides: Synthesis of [1,2,4]oxadiazolo[4,5-c]pyrimidine-5,7(6H)-dione derivatives

Author:
Kun-Ming Jiang; Yi Jin; Jun Lin
Source:
Tetrahedron 2017 pp. -
ISSN:
0040-4020
Subject:
bioactive properties; chemical reactions; chemical structure; oxides; uracil; uracil derivatives
Abstract:
... An efficient method of synthesizing bicyclic fused [1,2,4]oxadiazolo[4,5-c]pyrimidine-5,7(6H)-dione derivatives was developed through a [3 + 2] cycloaddition of uracil derivatives and nitrile oxides. In the one step reaction, CN and CO bonds were constructed, the target compounds were efficiently obtained in good yields. The method represents a valuable way to obtain highly functional fused bicycl ...
DOI:
10.1016/j.tet.2017.10.024

17. 1,4-Dicarbofunctionalization of 4-Fluoroaryl Grignard and Lithium Reagents with Disubstituted Malononitriles

Author:
Malapit Christian A.; Luvaga Irungu K.; Reeves Jonathan T.; Volchkov Ivan; Busacca Carl A.; Howell Amy R.; Senanayake Chris H.
Source:
Journal of organic chemistry 2017 v.82 no.9 pp. 4993-4997
ISSN:
1520-6904
Subject:
Grignard reagents; aromatic hydrocarbons; bromine; chemical reactions; chemical structure; lithium; magnesium; organic chemistry
Abstract:
... An efficient one-pot 1,4-dicarbofunctionalization of 4-fluoroaryl Grignard or lithium reagents with 2,2-disubstituted malononitriles is described. The reaction proceeds by sequential transnitrilation and SNAr reactions. Commercial Grignard solutions, Grignard reagents prepared in situ by halogen/magnesium exchange with i-PrMgCl, or aryllithium reagents prepared in situ by bromine/lithium exchange ...
DOI:
10.1021/acs.joc.7b00567

18. 1-Butyl-3-methylimidazol-2-ylidene Borane: A Readily Available, Liquid N-Heterocyclic Carbene Borane Reagent

Author:
Bolt Daniel A.; Curran Dennis P.
Source:
Journal of organic chemistry 2017 v.82 no.24 pp. 13746-13750
ISSN:
1520-6904
Subject:
bromides; carbenes; chemical reactions; chemical structure; heterocyclic nitrogen compounds; liquids; organic chemistry; sodium
Abstract:
... 1-Butyl-3-methylimidazol-2-ylidene borane has been synthesized directly from two inexpensive commercial reagents: 1-butyl-3-methylimidazolium bromide and sodium borohydride. This NHC-borane reagent is a stable, free-flowing liquid that shows promise for use in radical, ionic, and metal-catalyzed reactions. ...
DOI:
10.1021/acs.joc.7b02730

19. 1-Naphthylmethyl and 1-naphthylmethoxymethyl protecting groups: New members of the benzyl- and benzyloxymethyl-type family

Author:
Takuya Sato; Yohei Joh; Tohru Oishi; Kohei Torikai
Source:
Tetrahedron letters 2017 pp. -
ISSN:
0040-4039
Subject:
Lewis bases; acids; ambient temperature; ceric ammonium nitrate; chemical structure; organic compounds; oxidation
Abstract:
... 1-Naphthylmethyl (NAPI) and 1-naphthylmethoxymethyl (NAPOMI) protecting groups were developed as new members of the benzyl- and benzyloxymethyl-type family. NAPI and NAPOMI can be introduced under conventional conditions, such as NAPIBr/NaH/room temperature (rt), or NAPOMICl/i-Pr2EtN/rt. They can also be removed under conventional conditions, e.g., by dichlorodicyanobenzoquinone (DDQ)- or ceric am ...
DOI:
10.1016/j.tetlet.2017.04.046

20. 1-Trifluoromethylisoquinolines from α-Benzylated Tosylmethyl Isocyanide Derivatives in a Modular Approach

Author:
Lin Wang; Armido Studer
Source:
Organic letters 2017 v.19 no.20 pp. 5701-5704
ISSN:
1523-7052
Subject:
catalysts; catalytic activity; chemical reactions; chemical structure; organic compounds
Abstract:
... The preparation of various 1-trifluoromethylisoquinolines from α-benzylated tosylmethyl isocyanide derivatives and the commercial Togni reagent using a radical cascade is reported. The starting isocyanides are readily prepared in a modular sequence from commercial tosylmethyl isocyanide via sequential double α-alkylation, and the radical reaction proceeds under mild conditions with high efficiency ...
DOI:
10.1021/acs.orglett.7b02882

21. A 1-hydroxy-2,3,1-benzodiazaborine-containing π-conjugated system: Synthesis, optical properties and solvent-dependent response toward anions

Author:
Yusuke Satta; Ryuhei Nishiyabu; Tony D. James; Yuji Kubo
Source:
Tetrahedron 2017 pp. -
ISSN:
0040-4020
Subject:
anions; boron; chemical reactions; chemical structure; colorimetry; dimethyl sulfoxide; fluorescence; hydrogen bonding; nuclear magnetic resonance spectroscopy; optical properties; solvents; spectral analysis
Abstract:
... Our interest in the functionalization of OH-substituted azaborines prompted us to synthesize a 1-hydroxy-2,3,1-benzodiazaborine conjugated with 1,8-naphthalimide 1. Its fluorescence was dramatically affected by the nature of the solvent. In particular, the use of DMSO, which has a relatively high donor number (DN = 29.8), led to a remarkable decrease in the fluorescence intensity (ΦF = 0.0014), po ...
DOI:
10.1016/j.tet.2017.02.050

22. 13C NMR spectroscopic studies of the behaviors of carbonyl compounds in various solutions

Author:
Yoshikazu Hiraga; Saori Chaki; Satomi Niwayama
Source:
Tetrahedron letters 2017 pp. -
ISSN:
0040-4039
Subject:
carbonyl compounds; chemical reactions; chemical structure; hydrogen bonding; nuclear magnetic resonance spectroscopy; solvents; spectral analysis
Abstract:
... 13C NMR spectroscopic studies were performed for carbonyl compounds having a hydroxyl group, a carboalkoxy group, an acetoxy group, or a carboxyl group in various solvents with different polarities for observation of their behaviors of 13C NMR chemical shifts of carbonyl carbons in solutions. It was found that the chemical shifts of the carbonyl carbons in 13C NMR have good correlation with the em ...
DOI:
10.1016/j.tetlet.2017.10.071

23. 13C-Labeled Idohexopyranosyl Rings: Effects of Methyl Glycosidation and C6 Oxidation on Ring Conformational Equilibria

Author:
Bose-Basu Bidisha; Zhang Wenhui; Kennedy Jamie L. W.; Hadad Matthew J.; Carmichael Ian; Serianni Anthony S.
Source:
Journal of organic chemistry 2017 v.82 no.3 pp. 1356-1370
ISSN:
1520-6904
Subject:
aqueous solutions; chemical structure; conformational isomerization; methodology; molecular dynamics; organic chemistry; organic compounds; oxidation; pH
Abstract:
... An ensemble of JHH, JCH, and JCC values was measured in aqueous solutions of methyl α- and β-d-idohexopyranosides containing selective ¹³C-enrichment at various carbons. By comparing these J-couplings to those reported previously in the α- and β-d-idohexopyranoses, methyl glycosidation was found to affect ring conformational equilibria, with the percentages of ⁴C₁ forms based on ³JHH analysis as f ...
DOI:
10.1021/acs.joc.6b02399

24. 1H NMR-based kinetic and theoretical studies of the simultaneous formation of two discrete rotameric systems of a novel difenchyl sulfite ester

Author:
Alicia Singh; Perry T. Kaye; Kevin A. Lobb
Source:
Tetrahedron 2017 pp. -
ISSN:
0040-4020
Subject:
chemical reactions; chemical structure; models; nuclear magnetic resonance spectroscopy; organic compounds; quantum mechanics; spectral analysis; sulfites
Abstract:
... Attempted repetition of a reported synthesis of fenchene from fenchol has afforded, in high overall yield, a mixture shown by spectroscopic and elemental analysis to comprise a pair of discrete rotameric systems of a novel 2-endo-2′-endo-difenchyl sulfite ester. The kinetics of the formation of these dimeric rotameric systems (I and II) has been explored experimentally, using 1H NMR spectroscopic ...
DOI:
10.1016/j.tet.2017.10.059

25. 2-(Trimethylsilyl)phenyl Trimethylsilyl Ethers as Stable and Readily Accessible Benzyne Precursors

Author:
Ikawa Takashi; Masuda Shigeaki; Nakajima Hiroki; Akai Shuji
Source:
Journal of organic chemistry 2017 v.82 no.8 pp. 4242-4253
ISSN:
1520-6904
Subject:
chemical reactions; chemical structure; ethers; fluorides; organic chemistry; phenols; tetrabutylammonium compounds
Abstract:
... Stable 2-(trimethylsilyl)phenyl trimethylsilyl ethers, readily obtained from the corresponding halogenated phenols in two steps, were identified as novel benzyne precursors. These species were converted to benzynes by a domino reaction of O-desilylation, O-nonaflylation, and β-elimination under mild conditions using nonafluorobutanesulfonyl fluoride (NfF) and tetrabutylammonium triphenyldifluorosi ...
DOI:
10.1021/acs.joc.7b00238

26. 2-Hydroxyindoline-3-triethylammonium Bromide: A Reagent for Formal C3-Electrophilic Reactions of Indoles

Author:
Abe Takumi; Suzuki Takuro; Anada Masahiro; Matsunaga Shigeki; Yamada Koji
Source:
Organic letters 2017 v.19 no.16 pp. 4275-4278
ISSN:
1523-7052
Subject:
Lewis bases; bromides; chemical reactions; chemical structure; indoles; oxygen
Abstract:
... A novel indole-2,3-epoxide equivalent, 2-hydroxyindoline-3-triethylammonium bromide, was found to be a convenient reagent for formal C3-electrophilic reactions of indoles with various nucleophiles. By taking advantage of the nucleophilic character of the oxygen of the 2-hydroxyindoline, the interrupted retro-Claisen and interrupted Feist–Bénary reactions with 1,3-dicarbonyl compounds were efficie ...
DOI:
10.1021/acs.orglett.7b01940

27. 2D hetero-structures based on transition metal dichalcogenides: Fabrication, properties and applications

Author:
Ping Liu; Bin Xiang
Source:
Science bulletin 2017 pp. -
ISSN:
2095-9273
Subject:
chemical structure; physical properties; synthesis; van der Waals forces
Abstract:
... Recently, two dimensional transition metal dichalcogenides MX2 (M=Mo, W, etc; X=S, Se, Te) have ignited immense interests because of their unique structural and physical properties for the potential applications in the nano-optoelectronics, valley-spintronics etc. In terms of the structural compatibility and van der Waals interaction, two dimensional (2D) MX2 layers can be fabricated into various ...
DOI:
10.1016/j.scib.2017.08.007

28. 2D-IR Spectroscopy Shows that Optimized DNA Minor Groove Binding of Hoechst33258 Follows an Induced Fit Model

Author:
Ramakers Lennart A. I.; Hithell Gordon; May John J.; Greetham Gregory M.; Donaldson Paul M.; Towrie Michael; Parker Anthony W.; Burley Glenn A.; Hunt Neil T.
Source:
Journal of physical chemistry 2017 v.121 no.6 pp. 1295-1303
ISSN:
1520-5207
Subject:
DNA; chemical structure; hydrogen bonding; infrared spectroscopy; ligands; models
Abstract:
... The induced fit binding model describes a conformational change occurring when a small molecule binds to its biomacromolecular target. The result is enhanced noncovalent interactions between the ligand and biomolecule. Induced fit is well-established for small molecule–protein interactions, but its relevance to small molecule–DNA binding is less clear. We investigate the molecular determinants of ...
DOI:
10.1021/acs.jpcb.7b00345

29. 2H-Pyran-2-ones and their annelated analogs as multifaceted building blocks for the fabrication of diverse heterocycles

Author:
Ramendra Pratap; Vishnu Ji Ram
Source:
Tetrahedron 2017 v.73 pp. 2529-2590
ISSN:
0040-4020
Subject:
Lewis bases; bioactive properties; carbon; chemical reactions; chemical structure; dibenzofuran; isocoumarins; isoquinolines; nitrogen; oxazoles; oxygen; pyridines; pyrroles; quinolines; sulfur; thiazoles
Abstract:
... 2H-Pyran-2-ones are widely present in nature and found as either isolated or in fused form. Depending on the fusion of benzene ring, pyran can give coumarins, isocoumarins, dibenzopyrans etc. This class of molecules exhibit excellent biological activity and photophysical properties. Apart from these, 2H-pyran-2-one also acts as very good Michael acceptor, therefore act as very important synthetic ...
DOI:
10.1016/j.tet.2017.02.028

30. 3,14-Bis(4-formylphenyl)-17,17-di(n-pentyl)tetrabenzo[a,c,g,i]fluorene showing solvatochromism and crystallochromism in fluorescence

Author:
Masanori Ueki; Yusuke Kimura; Yuma Yamamoto; Jun-ich Nishida; Chitoshi Kitamura; Mirai Tanaka; Hiroshi Ikeda; Takeshi Kawase
Source:
Tetrahedron 2017 pp. -
ISSN:
0040-4020
Subject:
chemical reactions; chemical structure; fluorenes; fluorescence; methylene chloride; optical properties; prediction
Abstract:
... The substituent effect on optical properties of 3,14-diphenyl-17,17-di(n-pentyl)tetrabenzofluorene derivatives bearing electron-withdrawing groups (NC, CH3OCO, CH3SO2, and OHC) at 4-position of the phenyl groups were investigated. These compounds were readily prepared by using Suzuki–Miyaura cross-coupling as a key step. The 4-cyano, 4-methoxycarbonyl, and 4-methylsulfonyl derivatives display inte ...
DOI:
10.1016/j.tet.2017.01.014

31. 3,4,5-Trimethylphenol and Lewis Acid Dual-Catalyzed Cascade Ring-Opening/Cyclization: Direct Synthesis of Naphthalenes

Author:
Ma He; Hu Xiu-Qin; Luo Yong-Chun; Xu Peng-Fei
Source:
Organic letters 2017 v.19 no.24 pp. 6666-6669
ISSN:
1523-7052
Subject:
Lewis acids; catalysts; chemical bonding; chemical reactions; chemical structure; cleavage (chemistry); naphthalenes
Abstract:
... A 3,4,5-trimethylphenol and Lewis acid dual-catalyzed cascade reaction of donor–acceptor (D–A) cyclopropanes via ring-opening and cyclization is developed. In this reaction, a phenolic compound was used as a covalent catalyst for the first time. Additionally, control experiments proved that 3,4,5-trimethylphenol completed the catalytic cycle by accomplishing the C–C bond cleavage. Using this strat ...
DOI:
10.1021/acs.orglett.7b03392

32. 3,4-Dihydroisocoumarin derivatives from the marine-derived fungus Paraconiothyrium sporulosum YK-03

Author:
Li-Hua Zhang; Sheng-Ge Li; Hong-Hua Wu; Gang Chen; Li Li; Jiao Bai; Hui-Ming Hua; Hai-Feng Wang; Yue-Hu Pei
Source:
Phytochemistry letters 2017 v.20 pp. 200-203
ISSN:
1874-3900
Subject:
anticarcinogenic activity; chemical structure; circular dichroism spectroscopy; cytotoxicity; fungi; high performance liquid chromatography; humans; neoplasms
Abstract:
... Two new 3,4-dihydroisocoumarin derivatives, (3S, 4S)-4,5-dihydroxymellein (1) and R-(−)-mellein-8-O-β-d-glucopyranoside (2), together with six known analogs (3–8) were isolated from the marine-derived fungus Paraconiothyrium sporulosum YK-03. Their structures including absolute configurations were elucidated by extensive spectroscopic methods in combination with computational electronic circular d ...
DOI:
10.1016/j.phytol.2017.04.039

33. 3-(2-Azidoethyl)oxindoles: Advanced Building Blocks for One-Pot Assembly of Spiro[pyrrolidine-3,3′-oxindoles]

Author:
Akaev Andrey A.; Villemson Elena V.; Vorobyeva Nataliya S.; Majouga Alexander G.; Budynina Ekaterina M.; Melnikov Mikhail Ya
Source:
Journal of organic chemistry 2017 v.82 no.11 pp. 5689-5701
ISSN:
1520-6904
Subject:
Lewis bases; azides; chemical reactions; chemical structure; cytotoxicity; in vitro studies; neoplasm cells; organic chemistry
Abstract:
... A new synthetic approach to biologically relevant spiro[pyrrolidine-3,3′-oxindoles] was developed on the basis of the cascade transformation of 3-(2-azidoethyl)oxindoles via Staudinger/aza-Wittig/Mannich reactions. The parent azides were readily synthesized through a nucleophilic ring opening of spiro[cyclopropane-1,3′-oxindoles] with the azide ion. A series of new spiro[pyrrolidine-3,3′-oxindoles ...
DOI:
10.1021/acs.joc.7b00529

34. 3-Acylindoles Synthesis: Ruthenium-Catalyzed Carbonylative Coupling of Indoles and Aryl Iodides

Author:
Wang Zechao; Yin Zhiping; Wu Xiao-Feng
Source:
Organic letters 2017 v.19 no.17 pp. 4680-4683
ISSN:
1523-7052
Subject:
carbon-hydrogen bond activation; chemical reactions; chemical structure; indoles; ketones; molybdenum; organoiodine compounds
Abstract:
... A novel and convenient procedure for the synthesis of 3-acylindoles from simple indoles and aryl iodides has been established. Through ruthenium-catalyzed carbonylative C–H functionalization of indoles, with Mo(CO)₆ as the solid CO source, the desired indol-3-yl aryl ketones were isolated in moderate to good yields. Not only N-alkylindoles but also N-H indoles can be applied here. ...
DOI:
10.1021/acs.orglett.7b02320

35. 3-Hydroxy-2-(trialkylsilyl)phenyl Triflate: A Benzyne Precursor Triggered via 1,3-C-sp2-to-O Silyl Migration

Author:
Kwon Yong-Ju; Jeon Young-Kyo; Sim Ha-Bin; Oh In-Young; Shin Inji; Kim Won-Suk
Source:
Organic letters 2017 v.19 no.22 pp. 6224-6227
ISSN:
1523-7052
Subject:
chemical reactions; chemical structure; phenol; regioselectivity
Abstract:
... 3-Hydroxy-2-(trialkylsilyl)phenyl triflates are presented as new versatile hydroxyaryne precursors. These are base-activated aryne precursors induced via a C-sp²-to-O 1,3-Brook rearrangement. The reaction of various arynophiles and 3-trialkylsiloxybenzyne generated from 3-hydroxy-2-(trialkylsilyl)phenyl triflate efficiently afforded highly regioselective phenol derivatives. Furthermore, through cr ...
DOI:
10.1021/acs.orglett.7b03160

36. 3-Methyl-4-nitro-5-isatylidenyl-isoxazoles as 1,3-dipolarophiles for synthesis of polycyclic 3,3′-pyrrolidinyl-dispirooxindoles and their biological evaluation for anticancer activities

Author:
Bing Lin; Wen-Hui Zhang; Dan-Dan Wang; Yi Gong; Qi-Di Wei; Xiong-Li Liu; Ting-Ting Feng; Ying Zhou; Wei-Cheng Yuan
Source:
Tetrahedron 2017 pp. -
ISSN:
0040-4020
Subject:
antineoplastic activity; chemical elements; chemical reactions; chemical structure; organic compounds; proline
Abstract:
... Developed herein is a diversity-oriented one-pot multicomponent synthesis of polycyclic 3,3′- pyrrolidinyl-dispirooxindoles 3via a multicomponent 1,3-dipolar cycloaddition event of 3-methyl-4-nitro-5-isatylidenyl-isoxazoles 2 with azomethine ylides (thermally generated in situ from isatins and proline or thioproline). Products bearing four consecutive stereocenters consist of two oxindole moieties ...
DOI:
10.1016/j.tet.2017.07.011

37. 3-Methylene-4-amido-1,2-diazetidine as a Formal 1,4-Dipole Precursor: Lewis Acid-Catalyzed Nucleophilic Addition with Silylated Nucleophiles

Author:
Okitsu Takashi; Kobayashi Keiko; Kan Ryosuke; Yoshida Yuji; Matsui Yuki; Wada Akimori
Source:
Organic letters 2017 v.19 no.17 pp. 4592-4595
ISSN:
1523-7052
Subject:
Lewis bases; chemical structure; cycloaddition reactions; silyl enol ethers
Abstract:
... 3-Methylene-4-amido-1,2-diazetidine (MADA) was prepared for the first time via formal [2 + 2] cycloaddition of an allenamide and an azodicarboxylate. MADA worked as a formal 1,4-dipole precursor toward nucleophilic addition with various silyl enol ethers and allyltrimethylsilanes. ...
DOI:
10.1021/acs.orglett.7b02194

38. 3D Printing Polymers with Supramolecular Functionality for Biological Applications

Author:
Pekkanen Allison M.; Mondschein Ryan J.; Williams Christopher B.; Long Timothy E.
Source:
Biomacromolecules 2017 v.18 no.9 pp. 2669-2687
ISSN:
1526-4602
Subject:
adhesion; chemical structure; drugs; hydrogen bonding; manufacturing; mechanical properties; medical equipment; polymers; tissue scaffolds; viscoelasticity
Abstract:
... Supramolecular chemistry continues to experience widespread growth, as fine-tuned chemical structures lead to well-defined bulk materials. Previous literature described the roles of hydrogen bonding, ionic aggregation, guest/host interactions, and π–π stacking to tune mechanical, viscoelastic, and processing performance. The versatility of reversible interactions enables the more facile manufactur ...
DOI:
10.1021/acs.biomac.7b00671

39. 4-(Azulen-1-yl) six-membered heteroaromatics substituted in 2- and 6- positions with 2-(2-furyl)vinyl, 2-(2-thienyl)vinyl or 2-(3-thienyl)vinyl moieties

Author:
Liviu Birzan; Mihaela Cristea; Constantin C. Draghici; Victorita Tecuceanu; Anamaria Hanganu; Eleonora-Mihaela Ungureanu; Alexandru C. Razus
Source:
Tetrahedron 2017 pp. -
ISSN:
0040-4020
Subject:
ammonium acetate; chemical reactions; chemical structure; metal ions; perchlorates; pyridines; redox potential
Abstract:
... The synthesis of pyrylium and pyridinium salts and pyridines with azulene-1-yl moieties in position 4 and two 2-heteroarylvinyl groups in positions 2 and 6 was accomplished. The pyrylium salts were obtained starting from pyranones and pyridines could be prepared from these salts by treating them with ammonium acetate. The general procedures for the synthesis of pyridinium salts, which occur with g ...
DOI:
10.1016/j.tet.2017.03.035

40. 4-Aminoantipyrine in carbohydrate research: Design, synthesis and anticancer activity of thioglycosides of a novel class of 4-aminoantipyrines and their corresponding pyrazolopyrimidine and pyrazolopyridine thioglycosides

Author:
Galal H. Elgemeie; Mamdouh A. Abu-Zaied; Samah A. Loutfy
Source:
Tetrahedron 2017 pp. -
ISSN:
0040-4020
Subject:
antineoplastic activity; antipyrine; breasts; chemical reactions; chemical structure; colon; colorectal neoplasms; cytotoxicity; humans; liver; liver neoplasms; neoplasm cells; nuclear magnetic resonance spectroscopy; sodium; spectral analysis
Abstract:
... A convenient method for the synthesis of antipyrine, pyrazolopyrimidine and pyrazolopyridine thioglycosides was developed. This study reports a novel and efficient method for the synthesis of thioglycosides of a novel class of 4-aminoantipyrines 6a,b; 13a,b and their corresponding pyrazolopyrimidine thioglycosides 7a,b; 9a,b and pyrazolopyridine thioglycosides 14a,b; 16a,b. These series of compoun ...
DOI:
10.1016/j.tet.2017.08.024

41. 4-Diazoisochroman-3-imines: A Class of Metal Carbene Precursors for the Synthesis of Isochromene Derivatives

Author:
Ren Anni; Lang Bo; Lin Jialun; Lu Ping; Wang Yanguang
Source:
Journal of organic chemistry 2017 v.82 no.20 pp. 10953-10959
ISSN:
1520-6904
Subject:
alkenes; alkynes; carbenes; catalytic activity; chemical reactions; chemical structure; imidoesters; organic chemistry; pyrroles
Abstract:
... 4-Diazoisochroman-3-imines were investigated for their synthetic applications as a new class of metal carbene precursors. Under the catalysis from a Rh(II) complex, this class of α-diazo imidates reacted with alkenes and conjugated dienes through a formal [2 + 1] (i.e., cyclopropanation) or [4 + 3] cycloaddition to furnish spiro[cyclopropane-1,4′-isochroman]-3′-imines and tetrahydroisochromeno[3,4 ...
DOI:
10.1021/acs.joc.7b01860

42. 4-Trichloroacetyl-1,2,3-triazoles: A versatile building block for rapid assessment of carbohydrazides and rufinamide derivatives

Author:
Helio G. Bonacorso; Francieli M. Libero; Fábio M. Luz; Maiara C. Moraes; Susiane Cavinatto; Felipe S. Stefanello; Melissa B. Rodrigues; Nilo Zanatta; Marcos A.P. Martins
Source:
Tetrahedron letters 2017 v.58 pp. 3827-3830
ISSN:
0040-4039
Subject:
azides; cycloaddition reactions; bioactive properties; triazoles; rapid methods; chemical structure
Abstract:
... This work reports the synthesis of a series of (1H-1,2,3-triazol-4-yl)carbohydrazides (2), which were obtained from 4-trichloroacetyl-1H-1,2,3-triazoles (1). Triazoles 1 were synthesized by 1,3-dipolar cycloaddition reaction, starting from 4-alkoxy-1,1,1-trichloroalk-3-en-2-ones and benzyl azides and easily (15min) converted to 2 by reaction with hydrazine hydrate (73–82% yield). Carbohydrazides 2 ...
DOI:
10.1016/j.tetlet.2017.08.049

43. 4Z- and 4E-12-deoxydihydrokromycins, two naturally occurring kromycin aglycons of pikromycin from Streptomyces sp

Author:
Inho Yang; Jisoo Yoon; Dayoung Kim; Dongyup Hahn; Sang-Jip Nam; William Fenical
Source:
Tetrahedron letters 2017 pp. -
ISSN:
0040-4039
Subject:
Streptomyces; X-ray diffraction; bacteria; chemical reactions; chemical structure; circular dichroism spectroscopy; culture media; high performance liquid chromatography; macrolides; spectral analysis; stereochemistry
Abstract:
... HPLC-UV guided isolation for the culture broth extract of the marine-derived bacterium Streptomyces sp. has led to the two 14-membered macrolides, 4Z- (1) and 4E-12-dehydroxykromycins (2). The chemical structures of compounds 1 and 2 were elucidated by spectral data, while the absolute stereochemistry of 1 and 2 were determined by application of circular dichroism (CD) and analysis of X-ray crysta ...
DOI:
10.1016/j.tetlet.2017.03.088

44. 5-Nitroso-1,3-diphenyltetrazolium salt as a mediator for the oxidation of alcohols

Author:
Yuta Matsukawa; Tsunehisa Hirashita; Shuki Araki
Source:
Tetrahedron 2017 pp. -
ISSN:
0040-4020
Subject:
X-radiation; acetonitrile; alcohols; carbonyl compounds; chemical structure; nitric acid; oxidation
Abstract:
... We describe the synthesis of a mesoion-derived nitroso compound, 5-nitroso-1,3-diphenyltetrazolium tetrafluoroborate (1), and its application in the oxidation of alcohols. The structure of 1 was fully characterized by X-ray analysis, showing that it exists as a monomer in the solid state. In the cyclic voltammetric analysis of 1, a reversible redox peak was observed at 0.43 V (vs. Ag/Ag+ in MeCN) ...
DOI:
10.1016/j.tet.2017.08.055

45. A 7-Step Formal Asymmetric Total Synthesis of Strictamine via an Asymmetric Propargylation and Metal-Mediated Cyclization

Author:
Smith Myles W.; Zhou Zhiyao; Gao Alison X.; Shimbayashi Takuya; Snyder Scott A.
Source:
Organic letters 2017 v.19 no.5 pp. 1004-1007
ISSN:
1523-7052
Subject:
alkaloids; chemical structure; gold; oxidation
Abstract:
... Herein is shown how a novel catalytic asymmetric propargylation of 3,4-dihydro-β-carboline, followed by a designed Au(I)/Ag(I)-mediated 6-endo-dig cyclization, can directly deliver the indolenine-fused methanoquinolizidine core of the akuammiline alkaloid strictamine in its native oxidation state, ultimately achieving a 7-step formal asymmetric total synthesis. Also demonstrated are how the cycliz ...
DOI:
10.1021/acs.orglett.6b03839

46. 8-Propyldithieno[3,2-b:2′,3′-e]pyridine-3,5-diamine (DITIPIRAM) Derivatives as Neutral Receptors Tailored for Binding of Carboxylates

Author:
Cholewiak Agnieszka; Tycz Agnieszka; Jurczak Janusz
Source:
Organic letters 2017 v.19 no.11 pp. 3001-3004
ISSN:
1523-7052
Subject:
X-radiation; chemical reactions; chemical structure; geometry; hydrogen bonding; nuclear magnetic resonance spectroscopy; receptors; solvents; urea
Abstract:
... The DITIPIRAM (8-propyldithieno[3,2-b:2′,3′-e]pyridine-3,5-diamine)-based receptors 11 and 12 were readily synthesized, and their anion-binding properties were studied both in solution and in the solid-state. ¹H NMR titrations revealed that receptor 12 equipped with two phenyl-urea groups preferentially binds carboxylates, even in the highly competitive DMSO-d₆/CD₃OH solvent mixture. X-ray analysi ...
DOI:
10.1021/acs.orglett.7b01235

47. The AIEE properties and solid state fluorescence of 3-indolyl-4-indazolyl maleimide compounds: Synthesis and fluorescence characteristics

Author:
Bo-ye Zhu; Liang Han; Yu-Jin Li; Jian-rong Gao; Qing Ye
Source:
Tetrahedron 2017 pp. -
ISSN:
0040-4020
Subject:
chemical reactions; chemical structure; fluorescence; toluene
Abstract:
... A range of 3-indolyl-4-indazolyl maleimide fluorescent compounds, including 2a, 2b, 2c, 3a and 3b, were synthesized efficiently. In different organic dissolvents, the photo-physical performance was checked, either in the aggregated state or in the solid state. When being in solid and in solution state, these fluorescent compounds showed high fluorescent intensity, indicating a highest fluorescence ...
DOI:
10.1016/j.tet.2017.02.003

48. ATP Depletion Assay Led to the Isolation of New 36-Membered Polyol Macrolides Deplelides A and B from Streptomyces sp. MM581-NF15

Author:
Takeuchi Toshifumi; Hatano Masaki; Umekita Maya; Hayashi Chigusa; Wada Shun-ichi; Nagayoshi Miho; Sawa Ryuichi; Kubota Yumiko; Kawada Manabu; Igarashi Masayuki; Shibasaki Masakatsu
Source:
Organic letters 2017 v.19 no.16 pp. 4207-4210
ISSN:
1523-7052
Subject:
Streptomyces; adenosine triphosphate; assays; chemical reactions; chemical structure; databases; fractionation; inhibitory concentration 50; macrolides; neoplasm cells; nuclear magnetic resonance spectroscopy; polyols; spectral analysis; stereochemistry
Abstract:
... New 36-membered polyol macrolides deplelides A and B were isolated from the culture of Streptomyces MM581-NF15 by bioassay-guided fractionation using an ATP depletion assay. The planar structures of these novel compounds were identified by interpretation of the spectroscopic data (1D/2D NMR, MS, and IR). The relative stereochemistry was partially established using the universal NMR database method ...
DOI:
10.1021/acs.orglett.7b01807

49. Ab Initio Molecular Dynamic Simulations on Pd Clusters Confined in UiO-66-NH2

Author:
Chen De-Li; Wu Shengnan; Yang Pengyong; He Sihui; Dou Li; Wang Fang-Fang
Source:
The Journal of Physical Chemistry C 2017 v.121 no.16 pp. 8857-8863
ISSN:
1932-7455
Subject:
chemical structure; coordination polymers; deformation; encapsulation; energy; molecular dynamics; simulation models; thermodynamics
Abstract:
... The thermodynamically stable metal organic framework UiO-66-NH₂ has experimentally been demonstrated as an ideal platform to isolate metal clusters within its nanocages; however, the electronic structures and the dynamics of the encapsulated metal clusters are still unclear. Ab initio molecular dynamics simulations combined with density functional theory-based methods were employed to search the s ...
DOI:
10.1021/acs.jpcc.7b00957

50. About Underappreciated Yet Active Conformations of Thiourea Organocatalysts

Author:
Supady Adriana; Hecht Stefan; Baldauf Carsten
Source:
Organic letters 2017 v.19 no.16 pp. 4199-4202
ISSN:
1523-7052
Subject:
catalysts; catalytic activity; chemical reactions; chemical structure; hydrogen bonding; models; thiourea
Abstract:
... Conformational dynamics can define the function of organocatalysts. While the accepted mechanism of Schreiner’s catalyst features a double hydrogen bond to the substrate that only forms with the anti-anti conformation of its central thiourea group, our electronic-structure theory study reveals that binding of the model substrate methyl vinyl ketone prefers syn-anti conformations. We find a new mec ...
DOI:
10.1021/acs.orglett.7b01782

51. Absolute Configuration Assignment of Chiral Resorcin[4]arenes from ECD Spectra

Author:
Concilio Gerardo; Talotta Carmen; Gaeta Carmine; Neri Placido; Monaco Guglielmo; Zanasi Riccardo; Tedesco Daniele; Bertucci Carlo
Source:
Journal of organic chemistry 2017 v.82 no.1 pp. 202-210
ISSN:
1520-6904
Subject:
aromatic hydrocarbons; chemical structure; enantioselectivity; high performance liquid chromatography; models; optical isomerism; organic chemistry; stereochemistry; wavelengths
Abstract:
... Racemates of five chiral resorcin[4]arenes, four tetra-O-substituted and one hepta-O-substituted, have been resolved by enantioselective HPLC, and their ECD spectra have been recorded online by stopped-flow measurements. The absolute configuration has been assigned by comparison of the experimental ECD spectra with DFT and semiempirical calculations. For the four tetra-O-substituted resorcin[4]are ...
DOI:
10.1021/acs.joc.6b02349

52. Absolute Configurations of Griseorhodins A and C

Author:
Humberto E. Ortega; João M. Batista; Weilan G.P. Melo; Jon Clardy; Mônica T. Pupo
Source:
Tetrahedron letters 2017 pp. -
ISSN:
0040-4039
Subject:
Acromyrmex; Streptomyces puniceus; antibiotics; chemical reactions; chemical structure; circular dichroism spectroscopy; cytotoxicity; leaf-cutting ants; organic compounds
Abstract:
... The known antibiotic and cytotoxic compounds griseorhodin A (1) and griseorhodin C (2) were produced in solid culture by Streptomyces puniceus AB10, which was isolated from the leaf-cutter ant Acromyrmex rugosus rugosus. Their absolute configurations were unambiguously established as 6S,6aR,7S,8S and 6R,6aR,7S,8R, respectively, using vibrational circular dichroism (VCD) and density functional theo ...
DOI:
10.1016/j.tetlet.2017.11.008
PubMed:
29503481
PubMed Central:
PMC5828249

53. Absolute Molecular Orientation of Isopropanol at Ceria (100) Surfaces: Insight into Catalytic Selectivity from the Interfacial Structure

Author:
Doughty Benjamin; Goverapet Srinivasan Sriram; Bryantsev Vyacheslav S.; Lee Dongkyu; Lee Ho Nyung; Ma Ying-Zhong; Lutterman Daniel A.
Source:
The Journal of Physical Chemistry C 2017 v.121 no.26 pp. 14137-14146
ISSN:
1932-7455
Subject:
catalysts; catalytic activity; ceric oxide; chemical structure; isopropyl alcohol; methodology; models; physical phenomena; propylene
Abstract:
... The initial mechanistic steps underlying heterogeneous chemical catalysis can be described in a framework where the composition, structure, and orientation of molecules adsorbed to reactive interfaces are known. However, extracting this vital information is the limiting step in most cases due in part to challenges in probing the interfacial monolayer with enough chemical specificity to characteriz ...
DOI:
10.1021/acs.jpcc.7b03272

54. Absolute Stereochemical Determination of Asymmetric Sulfoxides via Central to Axial Induction of Chirality

Author:
Gholami Hadi; Zhang Jun; Anyika Mercy; Borhan Babak
Source:
Organic letters 2017 v.19 no.7 pp. 1722-1725
ISSN:
1523-7052
Subject:
chemical structure; optical isomerism; organic compounds; stereochemistry
Abstract:
... The absolute configuration of chiral sulfoxides is determined by means of host–guest complexation that leads to the induction of axial chirality in an achiral host. The central to axial induction of helicity is rationalized by a simple recognition of the relative length and size of the substituents attached to the S-center. This technique is used to determine the absolute configuration of chiral s ...
DOI:
10.1021/acs.orglett.7b00495

55. Absorption Tails of Donor:C60 Blends Provide Insight into Thermally Activated Charge-Transfer Processes and Polaron Relaxation

Author:
Vandewal Koen; Benduhn Johannes; Schellhammer Karl Sebastian; Vangerven Tim; Rückert Janna E.; Piersimoni Fortunato; Scholz Reinhard; Zeika Olaf; Fan Yeli; Barlow Stephen; Neher Dieter; Marder Seth R.; Manca Jean; Spoltore Donato; Cuniberti Gianaurelio; Ortmann Frank
Source:
Journal of the American Chemical Society 2017 v.139 no.4 pp. 1699-1704
ISSN:
1520-5126
Subject:
absorption; chemical structure; deformation; energy; geometry; methodology; photons; semiconductors
Abstract:
... In disordered organic semiconductors, the transfer of a rather localized charge carrier from one site to another triggers a deformation of the molecular structure quantified by the intramolecular relaxation energy. A similar structural relaxation occurs upon population of intermolecular charge-transfer (CT) states formed at organic electron donor (D)–acceptor (A) interfaces. Weak CT absorption ban ...
DOI:
10.1021/jacs.6b12857

56. Accelerated ageing and degradation characteristics of rigid polyurethane foam

Author:
Nazdaneh Yarahmadi; Alberto Vega; Ignacy Jakubowicz
Source:
Polymer Degradation and Stability 2017 v.138 pp. 192-200
ISSN:
0141-3910
Subject:
adhesion; air; chemical structure; foams; modulus of rupture; nitrogen; pentane; pipes; polyurethanes; prediction; shear strength; steel; thermal degradation; volatile compounds
Abstract:
... The urgent need for revision of the normative test method (EN 253) for the lifetime prediction of district heating pipes requires a better understanding of the failure mechanisms involved. Therefore, various methods were used to study thermal degradation characteristics of rigid polyurethane (PUR) foam in both air and nitrogen atmosphere. Accelerated ageing in nitrogen caused insignificant changes ...
DOI:
10.1016/j.polymdegradstab.2017.03.012

57. Access to 1a,6b-Dihydro-1H-benzofuro[2,3-b]azirines and Benzofuran-2-amines via Visible Light Triggered Decomposition of α-Azidochalcones

Author:
Borra Satheesh; Chandrasekhar D.; Khound Susmita; Maurya Ram Awatar
Source:
Organic letters 2017 v.19 no.19 pp. 5364-5367
ISSN:
1523-7052
Subject:
azirines; benzofurans; chemical structure; cyclization reactions; isomerization
Abstract:
... A novel, efficient, organic process that involves a photocatalyst-free visible light triggered decomposition of α-azidochalcones, followed by intramolecular cyclization, 1,2-acyl migration, and isomerization to construct benzofuran based molecular architectures, is described. The scope and limitation of the synthetic strategy were studied by synthesizing over 30 structurally diverse benzofurans in ...
DOI:
10.1021/acs.orglett.7b02643

58. Access to 8-Azachromones via Activation of C–H in N-Oxides

Author:
Wang Dong; Feng Hairong; Li Linna; Liu Zhenlin; Yan Zhongli; Yu Peng
Source:
Journal of organic chemistry 2017 v.82 no.20 pp. 11275-11287
ISSN:
1520-6904
Subject:
Lewis bases; chemical reactions; chemical structure; drugs; organic chemistry; organic compounds
Abstract:
... A concise and practical synthetic method has been developed for 8-azachromones, including 8-azaflavones, which have emerged as a promising class of compounds. Using commercially available nicotinates as the starting material, 8-azachromones were obtained in only three steps. The key intramolecular O-arylation reaction was achieved by nucleophilic attack of enolates to C2 of N-oxides under PyBrop o ...
DOI:
10.1021/acs.joc.7b02063

59. Access to Alkyl-Substituted Lactone via Photoredox-Catalyzed Alkylation/Lactonization of Unsaturated Carboxylic Acids

Author:
Sha Wanxing; Ni Shengyang; Han Jianlin; Pan Yi
Source:
Organic letters 2017 v.19 no.21 pp. 5900-5903
ISSN:
1523-7052
Subject:
alkylation; lactones; chemical structure; carboxylic acids
Abstract:
... An efficient photoredox-catalyzed alkylation/lactonization reaction of unsaturated carboxylic acids by using alkyl N-hydroxyphthalimide esters as alkylation reagents has been developed. Varieties of redox-active esters derived from aliphatic carboxylic acids were proved viable in this method, affording alkyl substituted lactones in moderate to good yields. This redox-neutral procedure features mil ...
DOI:
10.1021/acs.orglett.7b02899

60. Access to Aminated Saturated Oxygen Heterocycles via Copper-Catalyzed Aminooxygenation of Alkenes

Author:
Xie Jian; Wang Yue-Wei; Qi Lian-Wen; Zhang Bo
Source:
Organic letters 2017 v.19 no.5 pp. 1148-1151
ISSN:
1523-7052
Subject:
alkenes; amination; chemical structure; oxygen
Abstract:
... A copper-catalyzed aminooxygenation of unactivated alkenes with various O-nucleophiles is described. This novel methodology uses commercially available N-fluorobenzenesulfonimide as an amination reagent and provides a simple and efficient approach to a wide range of aminated saturated oxygen heterocycles in moderate to good yields. The reaction features mild reaction conditions, operational simpli ...
DOI:
10.1021/acs.orglett.7b00182

61. Access to Benzo[a]carbazoles and Indeno[1,2-c]quinolines by a Gold(I)-Catalyzed Tunable Domino Cyclization of Difunctional 1,2-Diphenylethynes

Author:
Peng Xiaoshi; Zhu Lifeng; Hou Yuqian; Pang Yadong; Li Yangming; Fu Jiayue; Yang Lu; Lin Bin; Liu Yongxiang; Cheng Maosheng
Source:
Organic letters 2017 v.19 no.13 pp. 3402-3405
ISSN:
1523-7052
Subject:
carbazoles; catalytic activity; chemical reactions; chemical structure; gold; methodology; nitrogen; quinoline
Abstract:
... The cyclization order of the difunctional 1,2-diphenylethynes was precisely tuned under the catalysis of gold by changing the nitrogen substitution of the substrates, leading to the facile preparation of benzo[a]carbazole and indeno[1,2-c]quinoline derivatives. The mechanisms of these domino cyclizations were probed by control experiments, and an insight into the selectivity of the cyclization was ...
DOI:
10.1021/acs.orglett.7b01358

62. Access to Chiral Seven-Member Cyclic Amines via Rh-Catalyzed Asymmetric Hydrogenation

Author:
Li Pan; Huang Yi; Hu Xinquan; Dong Xiu-Qin; Zhang Xumu
Source:
Organic letters 2017 v.19 no.14 pp. 3855-3858
ISSN:
1523-7052
Subject:
amines; chemical structure; chlorides; enantioselectivity; hydrogenation; imines; ligands; thiourea
Abstract:
... A highly efficient asymmetric hydrogenation of azepine/oxazepine-type seven-member cyclic imine hydrochlorides was successfully developed using Rh/bisphosphine-thiourea ligand ZhaoPhos, affording various chiral seven-member cyclic amines with full conversions, high yields, and excellent enantioselectivities (up to 96% yield, >99% ee). Additionally, this asymmetric hydrogenation can proceed well on ...
DOI:
10.1021/acs.orglett.7b01726

63. Access to Chiral Silicon Centers for Application to Circularly Polarized Luminescence Materials

Author:
Koga Shinya; Ueki Shuhei; Shimada Masaki; Ishii Ryoma; Kurihara Yu; Yamanoi Yoshinori; Yuasa Junpei; Kawai Tsuyoshi; Uchida Taka-aki; Iwamura Munetaka; Nozaki Koichi; Nishihara Hiroshi
Source:
Journal of organic chemistry 2017 v.82 no.12 pp. 6108-6117
ISSN:
1520-6904
Subject:
arylation; chemical structure; dyes; enantioselectivity; fluorescence; iodides; optical properties; organic chemistry; organic compounds; silane; silicon
Abstract:
... Asymmetric arylation of secondary silanes catalyzed by a Pd-chiral phosphoramidite complex was developed for application to low-molecular-weight circularly polarized luminescence (CPL) materials. The asymmetric arylation provided a convenient, efficient synthetic method for a variety of chiral tertiary silanes (2–21), which were key intermediates for preparing the quaternary silicon center. A step ...
DOI:
10.1021/acs.joc.7b00583

64. Access to Cyano-Containing Isoxazolines via Copper-Catalyzed Domino Cyclization/Cyanation of Alkenyl Oximes

Author:
Meng Fei; Zhang Honglin; Guo Kang; Dong Jiayue; Lu Ai-Min; Zhu Yingguang
Source:
Journal of organic chemistry 2017 v.82 no.19 pp. 10742-10747
ISSN:
1520-6904
Subject:
alkenes; catalysts; chemical bonding; chemical reactions; chemical structure; copper; cyanides; organic chemistry; oximes
Abstract:
... A highly efficient copper-catalyzed cyclization/cyanation cascade of unactivated olefins bearing oximes is described. A variety of cyano-containing isoxazolines have been obtained in high yields with cheap Cu(NO₃)₂·3H₂O as the catalyst and TMSCN as the non-metallic cyanide source. The present method provides a mild, simple, and practical access to cyano-substituted isoxazolines and is amenable to ...
DOI:
10.1021/acs.joc.7b02133

65. Access to Cyclobutadienes via an Organocatalytic Dienamine–Iminium–Allenamine Cascade Approach

Author:
Li Wenjun; Lang Ming; Wang Jian
Source:
Organic letters 2017 v.19 no.17 pp. 4564-4567
ISSN:
1523-7052
Subject:
aldehydes; catalytic activity; chemical reactions; chemical structure
Abstract:
... A new organocatalytic route to cyclobutadienes from α,β-unsaturated aldehydes and ynals is described. This protocol allows a broad substrate scope and mild conditions. Furthermore, a proposed mechanism of a dienamine–iminium–allenamine cascade process is discussed. ...
DOI:
10.1021/acs.orglett.7b02161

66. Access to Fused Tricyclic γ-Butyrolactones, A Natural Product-like Scaffold

Author:
Kalmode Hanuman P.; Handore Kishor L.; Reddy D. Srinivasa
Source:
Journal of organic chemistry 2017 v.82 no.14 pp. 7614-7620
ISSN:
1520-6904
Subject:
chemical structure; chemotypes; condensation reactions; organic chemistry; toluene
Abstract:
... Serendipitous findings of an acid mediated skeletal rearrangement of bicyclo-β-ketoester having cyclopropyl ring to access fused tricyclic γ-butyrolactones has been described. This novel transformation has been optimized to 30 mol% p-toluenesulfonic acid (p-TSA) in toluene using Dean–Stark apparatus, where the aldol condensation, cyclopropyl ring opening followed by cyclization took place in a sin ...
DOI:
10.1021/acs.joc.7b00794

67. Access to Perfluoroalkyl-Substituted Enones and Indolin-2-ones via Multicomponent Pd-Catalyzed Carbonylative Reactions

Author:
Yin Hongfei; Skrydstrup Troels
Source:
Journal of organic chemistry 2017 v.82 no.12 pp. 6474-6481
ISSN:
1520-6904
Subject:
acids; alkynes; carbon monoxide; catalytic activity; chemical reactions; chemical structure; iodides; organic chemistry; palladium
Abstract:
... A simple method for accessing perfluoroalkyl-substituted enones is described applying a four-component palladium-catalyzed carbonylative coupling of aryl boronic acids together with terminal alkynes and perfluoroalkyl iodides in the presence of carbon monoxide. A wide range of highly functionalized enones can thus be prepared in a single operation in good yields. With 2-aminophenylalkynes, an intr ...
DOI:
10.1021/acs.joc.7b00942

68. Access to Substituted Propenoic Acids via Rh(III)-Catalyzed C–H Allylation of (Hetero)Arenes with Methyleneoxetanones

Author:
Xia Jintao; Kong Lingheng; Zhou Xukai; Zheng Guangfan; Li Xingwei
Source:
Organic letters 2017 v.19 no.21 pp. 5972-5975
ISSN:
1523-7052
Subject:
acids; allylation; aromatic hydrocarbons; carbon-hydrogen bond activation; chemical structure
Abstract:
... An efficient synthesis of disubstituted acrylic acids has been realized via Rh(III)-catalyzed C–H activation of (hetero)arenes and coupling with four-membered methyleneoxetanones under redox-neutral conditions. In most cases, the reactions are silver-free, and the products are exclusively E-selective with a broad substrate scope. The transformation proceeds via ortho C–H activation followed by sel ...
DOI:
10.1021/acs.orglett.7b02983

69. Access to Substituted Trifluoromethyl Ketones Using the Versatile Synthetic Intermediate (E)-1,1-Dimethyl-2-(1,1,1-trifluoropropan-2-ylidene)hydrazine

Author:
Ted C. Judd; Derek B. Brown
Source:
Tetrahedron letters 2017 pp. -
ISSN:
0040-4039
Subject:
aldehydes; alkylation; bromides; catalytic activity; chemical structure; hydrazine; hydrolysis; ketones; palladium
Abstract:
... The N,N-dimethylhydrazone of 1,1,1-trifluoroacetone, (E)-1,1-dimethyl-2-(1,1,1-trifluoropropan-2-ylidene)hydrazine, has been shown to undergo a diverse set of reactions following deprotonation with n-butyl-lithium; including alkylation, addition to ketones and aldehydes, as well as palladium-catalyzed cross-couplings with aryl bromides. Mild hydrolysis of the N,N-dimethylhydrazone products from th ...
DOI:
10.1016/j.tetlet.2017.10.022

70. Access to Tetronic Acids via Silver-Catalyzed CO2 Incorporation into Conjugated Ynones

Author:
Sadamitsu Yuta; Komatsuki Keiichi; Saito Kodai; Yamada Tohru
Source:
Organic letters 2017 v.19 no.12 pp. 3191-3194
ISSN:
1523-7052
Subject:
acids; alkynes; carbon dioxide; catalysts; chemical structure; cyclization reactions; silver
Abstract:
... Facile and versatile access to highly functionalized tetronic acids has been successfully achieved through the reaction of conjugated ynones with carbon dioxide. In the presence of a base, the enolates generated from the ynones capture CO₂ via a carbon–carbon bond-forming reaction, accompanied by a 5-exo-dig cyclization reaction of the resulting carboxylate to the alkyne, activated by a silver cat ...
DOI:
10.1021/acs.orglett.7b01309

71. Access to a Guanacastepene and Cortistatin-Related Skeleton via Ethynyl Lactone Ireland–Claisen Rearrangement and Transannular (4 + 3)-Cycloaddition of an Azatrimethylenemethane Diyl

Author:
Zhurakovskyi Oleksandr; Ellis Sam R.; Thompson Amber L.; Robertson Jeremy
Source:
Organic letters 2017 v.19 no.8 pp. 2174-2177
ISSN:
1523-7052
Subject:
allene; chemical structure; cycloaddition reactions; nitrogen
Abstract:
... Heating a 2,5-furanocyclic (2-azidoethyl)allene initiates a cascade reaction comprising azide–allene cycloaddition, loss of nitrogen, and azatrimethylenemethane (ATMM) diyl–furan transannular (4 + 3)-cycloaddition. The major product of this reaction contains the pentacyclic core common to guanacastepenes D and H and radianspenes J–L; in addition, the central oxa-bridged cycloheptene ring, flanked ...
DOI:
10.1021/acs.orglett.7b00834

72. Access to polysubstituted naphthalenes and anthracenes via a retro-Diels–Alder reaction

Author:
Esra Turan Akin; Musa Erdogan; Arif Dastan; Nurullah Saracoglu
Source:
Tetrahedron 2017 pp. -
ISSN:
0040-4020
Subject:
alkenes; anthracenes; chemical reactions; chemical structure; naphthalene; physicochemical properties
Abstract:
... Naphthalene and anthracene nuclei are present in several natural and synthetic compounds. Due to their unique physical and chemical properties, access to functionalized naphthalenes and anthracenes has attracted the attention of both synthetic and medicinal chemists over the decades. In this study, successive Diels–Alder/retro-Diels–Alder reactions of dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate w ...
DOI:
10.1016/j.tet.2017.07.058

73. Accessing N-Acyl Azoles via Oxoammonium Salt-Mediated Oxidative Amidation

Author:
Ovian John M.; Kelly Christopher B.; Pistritto Vincent A.; Leadbeater Nicholas E.
Source:
Organic letters 2017 v.19 no.6 pp. 1286-1289
ISSN:
1523-7052
Subject:
alcohols; aldehydes; amides; azoles; chemical structure; esterification; oxidants
Abstract:
... An operationally simple, robust, metal-free approach to the synthesis of N-acyl azoles from both alcohols and aldehydes is described. Oxidative amidation is facilitated by a commercially available organic oxidant (4-acetamido-2,2,6,6-tetramethylpiperidine-1-oxoammonium tetrafluoroborate) and proceeds under very mild conditions for an array of structurally diverse substrates. Tandem reactions of th ...
DOI:
10.1021/acs.orglett.7b00060

74. Accessing Polyoxygenated Dibenzofurans via the Union of Phenols and o-Benzoquinones: Rapid Syntheses of Metabolites Isolated from Ribes takare

Author:
Zhang Meng Yao; Barrow Russell A.
Source:
Organic letters 2017 v.19 no.9 pp. 2302-2305
ISSN:
1523-7052
Subject:
Ribes; benzoquinones; carbon; chemical reactions; chemical structure; dibenzofuran; metabolites; naphthols
Abstract:
... The construction of polyoxygenated dibenzo[b,d]furan frameworks from the union of substituted phenols/naphthols and o-benzoquinones via a Michael-oxidation-oxa-Michael cascade is reported. The power of this transformation is demonstrated in the generation of a library of highly substituted dibenzofurans, featuring specifically substituted molecules containing broad ranges of functionality. The uti ...
DOI:
10.1021/acs.orglett.7b00840

75. Accurate Identification of Unknown and Known Metabolic Mixture Components by Combining 3D NMR with Fourier Transform Ion Cyclotron Resonance Tandem Mass Spectrometry

Author:
Wang Cheng; He Lidong; Li Da-Wei; Bruschweiler-Li Lei; Marshall Alan G.; Brüschweiler Rafael
Source:
Journal of Proteome Research 2017 v.16 no.10 pp. 3774-3786
ISSN:
1535-3907
Subject:
Escherichia coli; chemical structure; databases; metabolites; metabolomics; models; nuclear magnetic resonance spectroscopy; proteome; tandem mass spectrometry
Abstract:
... Metabolite identification in metabolomics samples is a key step that critically impacts downstream analysis. We recently introduced the SUMMIT NMR/mass spectrometry (MS) hybrid approach for the identification of the molecular structure of unknown metabolites based on the combination of NMR, MS, and combinatorial cheminformatics. Here, we demonstrate the feasibility of the approach for an untargete ...
DOI:
10.1021/acs.jproteome.7b00457
PubMed:
28795575
PubMed Central:
PMC5663437

76. Acetaminophen analog N-acetyl-m-aminophenol, but not its reactive metabolite, N-acetyl-p-benzoquinone imine induces CYP3A activity via inhibition of protein degradation

Author:
Masataka Santoh; Seigo Sanoh; Yuya Ohtsuki; Yoko Ejiri; Yaichiro Kotake; Shigeru Ohta
Source:
Biochemical and biophysical research communications 2017 pp. -
ISSN:
0006-291X
Subject:
acetaminophen; acetylcysteine; benzoquinones; chemical structure; cytochrome P-450; drug interactions; glutathione; messenger RNA; metabolites; protein degradation; transcription (genetics)
Abstract:
... Cytochrome P450 (CYP) 3A subfamily members are known to metabolize various types of drugs, highlighting the importance of understanding drug–drug interactions (DDI) depending on CYP3A induction or inhibition. While transcriptional regulation of CYP3A members is widely understood, post-translational regulation needs to be elucidated. We previously reported that acetaminophen (APAP) induces CYP3A ac ...
DOI:
10.1016/j.bbrc.2017.03.073

77. Acetic Acid Mediated Sulfonylation of Allenylphosphine Oxides: Divergent Synthesis of Bifunctionalized 1,3-Butadienes and Allenes

Author:
Luo Kai; Zhang Ling; Ma Jing; Sha Qiang; Wu Lei
Source:
Journal of organic chemistry 2017 v.82 no.13 pp. 6978-6985
ISSN:
1520-6904
Subject:
acetic acid; carbon; chemical structure; cleavage (chemistry); methodology; organic chemistry; oxides; reaction mechanisms; sodium; sulfonylation
Abstract:
... An acetic acid-mediated sulfonylation of allenylphosphine oxides with sodium sulfinates is disclosed. This new methodology involves tandem (Ar)O–C(sp³) bond cleavage and C(sp²)/C(sp³)–SO₂ formation toward divergent synthesis of sulfonyl- and phosphinyl-bifunctionalized 1,3-butadienes or allenes, depending on the substitution at the terminal carbon atoms of allenylphosphine oxides. The reaction mec ...
DOI:
10.1021/acs.joc.7b00813

78. Acetone promoted 1,4-migration of an alkoxycarbonyl group on a syn-1,2-diamine

Author:
Tanya Napolitano; Shu-Yuan Cheng; Brooke Nielsen; Christopher Choi; William Aguilar; Manuel M. Paz; Anne-Marie Sapse; Elise Champeil
Source:
Tetrahedron letters 2017 v.58 pp. 597-601
ISSN:
0040-4039
Subject:
acetone; chemical structure; isomerization
Abstract:
... A 2-protected cis-amino mitosene undergoes an irreversible acetone promoted isomerization and converts to the 1-isomer. Kinetic studies and DFT calculations of the reaction are reported. An organocatalytic mechanism is proposed, involving a covalent intermediate formed by reaction of the mitosene and acetone. ...
DOI:
10.1016/j.tetlet.2016.12.047
PubMed:
28943668
PubMed Central:
PMC5604470

79. Acetonitrile-dependent oxyphosphorylation: A mild one-pot synthesis of β-ketophosphonates from alkenyl acids or alkenes

Author:
Xi Chen; Xiaolan Chen; Xu Li; Chen Qu; Lingbo Qu; Wenzhu Bi; Kai Sun; Yufen Zhao
Source:
Tetrahedron 2017 pp. -
ISSN:
0040-4020
Subject:
acetonitrile; air; alkenes; carboxylic acids; chemical reactions; chemical structure; copper sulfate; oxygen; synthesis
Abstract:
... An efficient one-pot synthesis of β-ketophosphonates has been developed, via the reaction of α,β-alkenyl carboxylic acids or alkenes with H-phosphonates and air oxygen, catalyzed by CuSO4·5H2O in CH3CN. CH3CN plays a decisive role, probably by forming an active oxygen complex [(MeCN)nCuII-O-O·]. ...
DOI:
10.1016/j.tet.2017.03.026

80. Achieving Site Selectivity in Metal-Catalyzed Electron-Rich Carbene Transfer Reactions from N-Tosylhydrazones

Author:
Su Naijing; Deng Tianning; Wink Donald J.; Driver Tom G.
Source:
Organic letters 2017 v.19 no.15 pp. 3990-3993
ISSN:
1523-7052
Subject:
carbenes; carbon-hydrogen bond activation; catalysts; chemical bonding; chemical reactions; chemical structure; copper; diastereoselectivity; iodides; rhodium
Abstract:
... Catalyst control of the site-selectivity of electron-rich alkyl, aryl disubstituted carbenes generated in situ from o-alkenyl-substituted N-tosylhydrazones was achieved in this study. Exposure of these substrates to copper iodide triggered the formation of α-alkoxy 2H-naphthalenones. This investigation established that changing the catalyst to a rhodium(II) carboxylate turned off cyclization and m ...
DOI:
10.1021/acs.orglett.7b01694

81. Achieving branched polyethylene waxes by aryliminocycloocta[b]pyridylnickel precatalysts: Synthesis, characterization, and ethylene polymerization

Author:
Randi Zhang; Zheng Wang; Zygmunt Flisak; Xiang Hao; Qingbin Liu; Wen‐Hua Sun
Source:
Journal of polymer science 2017 v.55 no.16 pp. 2601-2610
ISSN:
0887-624X
Subject:
Fourier transform infrared spectroscopy; bromides; catalysts; chemical structure; chlorides; ethylene; ligands; microstructure; molecular weight; nickel; nuclear magnetic resonance spectroscopy; physical properties; polyethylene; polymerization; waxes
Abstract:
... Cycloocta[b]pyridin‐10‐one was prepared to form the corresponding imino derivatives, which then reacted with (DME)NiBr₂ to form 10‐aryliminocycloocta[b]pyridylnickel bromides (Ni1–Ni5). The new compounds were characterized by means of FT‐IR spectroscopy as well as elemental analysis and the organic ligands were also analyzed by the NMR measurements. Furthermore, the molecular structure of a repres ...
DOI:
10.1002/pola.28653

82. Acid Chlorides as Formal Carbon Dianion Linchpin Reagents in the Aluminum Chloride-Mediated Dieckmann Cyclization of Dicarboxylic Acids

Author:
Armaly Ahlam M.; Bar Sukanta; Schindler Corinna S.
Source:
Organic letters 2017 v.19 no.15 pp. 3962-3965
ISSN:
1523-7052
Subject:
aluminum; carbon; chemical structure; cyclization reactions; dicarboxylic acids; isotope labeling; organochlorine compounds; reaction mechanisms; stable isotopes
Abstract:
... The development of acid chlorides as formal dianion linchpin reagents that enable access to cyclic 2-alkyl- and 2-acyl-1,3-alkanediones from dicarboxylic acids is described herein. Mechanistic experiments relying on ¹³C-labeling studies confirm the role of acid chlorides as carbon dianion linchpin reagents and have led to a revised reaction mechanism for the aluminum(III)-mediated Dieckmann cycliz ...
DOI:
10.1021/acs.orglett.7b01623

83. Acid Promoted Direct Cross-Coupling of Methyl Ketones with Dimethyl Sulfoxide: Access to Ketoallyl Methylsulfides and -sulfones

Author:
Wen Zhen-Kang; Liu Xue-Hua; Liu Yu-Fang; Chao Jian-Bin
Source:
Organic letters 2017 v.19 no.21 pp. 5798-5801
ISSN:
1523-7052
Subject:
Lewis bases; chemical structure; cross-coupling reactions; dimethyl sulfoxide; enamines; ketones
Abstract:
... A new strategy to prepare β-acyl allylic methylsulfides and -sulfones through acid promoted direct cross-coupling of methyl ketones with dimethyl sulfoxide (DMSO) is reported. The reaction proceeded through the nucleophilic attack of enamine intermidiates derived from ketones to in situ generated thionium ion species, followed by elimination of methanthiol to give ketoallylic methylsulfides. With ...
DOI:
10.1021/acs.orglett.7b02753

84. Acid-Catalyzed Skeletal Rearrangements in Arenes: Aryl versus Alkyl Ring Pirouettes in Anthracene and Phenanthrene

Author:
Skraba-Joiner Sarah L.; Brulet Jeffrey W.; Song Min K.; Johnson Richard P.
Source:
Journal of organic chemistry 2017 v.82 no.24 pp. 13076-13083
ISSN:
1520-6904
Subject:
ambient temperature; anthracenes; chemical structure; isomerization; isotope labeling; models; nuclear magnetic resonance spectroscopy; organic chemistry; phenanthrenes
Abstract:
... In 1 M triflic acid/dichloroethane, anthracene is protonated at C9, and the resulting 9-anthracenium ion is easily observed by NMR at ambient temperature. When heated as a dilute solution in triflic acid/dichloroethane, anthracene undergoes conversion to phenanthrene as the major volatile product. Minor dihydro and tetrahydro products are also observed. MALDI analysis supports the simultaneous for ...
DOI:
10.1021/acs.joc.7b02058

85. Acid-Mediated Intermolecular [3 + 2] Cycloaddition toward Pyrrolo[2,1-a]isoquinolines: Total Synthesis of the Lamellarin Core and Lamellarin G Trimethyl Ether

Author:
Zheng Kai-Lu; You Min-Qi; Shu Wen-Ming; Wu Yan-Dong; Wu An-Xin
Source:
Organic letters 2017 v.19 no.9 pp. 2262-2265
ISSN:
1523-7052
Subject:
Lewis acids; Suzuki reaction; catalytic activity; chemical structure; cycloaddition reactions; isoquinolines; palladium
Abstract:
... A novel one-pot reaction has been developed for the efficient synthesis of pyrrolo[2,1-a]isoquinolines and 1-dearyllamellarin core from (E)-(2-nitrovinyl)benzenes and azomethine ylides generated in situ. This strategy provides a concise total synthesis of the lamellarin core and lamellarin G trimethyl ether using electrophilic substitution and palladium-catalyzed Suzuki–Miyaura cross-coupling reac ...
DOI:
10.1021/acs.orglett.7b00769

86. Acid-Mediated Migration of Bromide in an Antiaromatic Porphyrinoid: Preparation of Two Regioisomeric Ni(II) Bromonorcorroles

Author:
Kawashima Hiroyuki; Hiroto Satoru; Shinokubo Hiroshi
Source:
Journal of organic chemistry 2017 v.82 no.19 pp. 10425-10432
ISSN:
1520-6904
Subject:
bromides; bromination; chemical structure; hydrobromic acid; nickel; optical properties; organic chemistry; organic compounds; reaction mechanisms; regioselectivity
Abstract:
... The regioselective halogenation of porphyrinoids is critical for their selective functionalization, which enables the fine tuning of their electronic and optical properties. Here we report the synthesis of two regioisomeric Ni(II) bromonorcorroles on the basis of the acid-induced migration of the bromo substituent. Treatment of Ni(II) dimesitylnorcorrole with N-bromosuccinimide (NBS) selectively a ...
DOI:
10.1021/acs.joc.7b01899

87. Acid-mediated aryl migration reaction of C-3 aryl substituted pyrrolidinoindolines

Author:
Shinji Tadano; Hayato Ishikawa
Source:
Tetrahedron letters 2017 v.58 no.1 pp. 5-8
ISSN:
0040-4039
Subject:
chemical reactions; chemical structure; organic compounds
Abstract:
... Aryl migration reactions of C-3 aryl substituted pyrrolidinoindoline compounds to provide highly conjugated C-2 aryl indole compounds have been discovered. The developed reactions have a wide substrate scope and proceed in high yield under simple acidic conditions. A unique cationic cyclopropane intermediate as the transition state is proposed. ...
DOI:
10.1016/j.tetlet.2016.11.069

88. Acid-mediated domino reaction of ortho-carbonylated alkynyl-substituted arylaldehydes with phenols: Rapid access to fused indeno[2,1-c]chromen-7-one derivatives

Author:
Hongbo Zhu; Ziping Cao; Xin Meng; Laijin Tian; Guang Chen; Xuejun Sun; Jinmao You
Source:
Tetrahedron 2017 pp. -
ISSN:
0040-4020
Subject:
aldehydes; catalysts; chemical reactions; chemical structure; indans; phenols; stereochemistry
Abstract:
... Acid-mediated domino reaction of ortho-carbonylated alkynyl-substituted arylaldehydes with phenols is described. The implement of this reaction can provide directly a variety of tetracyclic indeno[2,1-c]chromen-7-one products in good yields. The mechanism was proposed to be a domino indanone ring formation/ortho-alkylation of phenols/dehydrated cyclization for the formation of polycyclic skeleton. ...
DOI:
10.1016/j.tet.2017.04.041

89. Acid/Phosphide-Induced Radical Route to Alkyl and Alkenyl Sulfides and Phosphonothioates from Sodium Arylsulfinates in Water

Author:
Lin Ya-mei; Lu Guo-ping; Wang Gui-xiang; Yi Wen-bin
Source:
Journal of organic chemistry 2017 v.82 no.1 pp. 382-389
ISSN:
1520-6904
Subject:
alkenes; alkynes; chemical reactions; chemical structure; free radicals; odors; organic chemistry; oxides; sodium; solvents; sulfides; thiols
Abstract:
... A newly developed aqueous system with acid and phosphide was introduced in which odorless and stable sodium arylsulfinates can in situ generate arylsulfenyl radicals. These radicals have high reactivity to react with alkynes, alkenes, and H-phosphine oxides for the synthesis of alkyl and alkenyl sulfides and phosphonothioates. The control experiments and quantum calculations are also performed to ...
DOI:
10.1021/acs.joc.6b02459

90. Acid/base controllable self-complexes that mimic flapping butterfly

Author:
Mujuan Chen; Jidong Liang; Zhijian Zeng; Xin Lin; Shilong Zhang; Lasheng Jiang
Source:
Tetrahedron letters 2017 v.58 pp. 3437-3440
ISSN:
0040-4039
Subject:
X-radiation; butterflies; chemical reactions; chemical structure; ethers; mass spectrometry; nuclear magnetic resonance spectroscopy
Abstract:
... A new type of self-complexed bis-crown ether containing two bis(p-phenylene)-34-crown-10 (BPP34C10) ether rings and two secondary ammoniums has been synthesized and characterized. The formation of these bis-self-complexes has been identified by NMR spectroscopy, mass spectrometry and X-ray analysis. The acid/base controlled movement of these bis–crown ethers can mimic a flapping butterfly. ...
DOI:
10.1016/j.tetlet.2017.07.067

91. An Acidity Scale of Triazolium-Based NHC Precursors in DMSO

Author:
Li Zhen; Li Xin; Cheng Jin-Pei
Source:
Journal of organic chemistry 2017 v.82 no.18 pp. 9675-9681
ISSN:
1520-6904
Subject:
acidity; carbenes; chemical reactions; chemical structure; dimethyl sulfoxide; heterocyclic nitrogen compounds; organic chemistry
Abstract:
... An acidity scale of triazolium-based N-heterocyclic carbene precursors was established by measuring 25 compounds’ (10a–15b) equilibrium acidities in dimethyl sulfoxide (DMSO) solution using overlapping indicator method. The pKₐ values ranged from 12.08 to 15.5, responding not only to the N-aryl motif, but also to the core structure. Excellent correlation was observed between the pKₐ values and the ...
DOI:
10.1021/acs.joc.7b01755

92. Acid–Base Properties of a Freebase Form of a Quadruply Ring-Fused PorphyrinStepwise Protonation Induced by Rigid Ring-Fused Structure

Author:
Saegusa Yuta; Ishizuka Tomoya; Shiota Yoshihito; Yoshizawa Kazunari; Kojima Takahiko
Source:
Journal of organic chemistry 2017 v.82 no.1 pp. 322-330
ISSN:
1520-6904
Subject:
X-ray diffraction; chemical reactions; chemical structure; electrochemistry; methylene chloride; nitrogen; nuclear magnetic resonance spectroscopy; organic chemistry; porphyrins; protons; pyrroles
Abstract:
... We report herein unique stepwise protonation at inner imino-nitrogen atoms of a freebase derivative of a quadruply fused porphyrin (H₂QFP), which has been newly synthesized. H₂QFP has been revealed to have the two inner NH protons on the two nonfused pyrroles by X-ray diffraction analysis and ¹H NMR spectroscopy. The first protonation at one of the two imino-nitrogen atoms of the fused pyrroles sm ...
DOI:
10.1021/acs.joc.6b02419

93. Acrylamide in Rauhut-Currier reaction; intramolecular isomerization of activated alkenes for quinolone synthesis

Author:
Kishor Chandra Bharadwaj
Source:
Tetrahedron 2017 pp. -
ISSN:
0040-4020
Subject:
acrylamides; alkenes; chalcone; chemical structure; isomerization; polymers; quinolones
Abstract:
... Acrylamides are fundamental Michael acceptors which have been used profoundly in synthetic, medicinal and polymer chemistry. However, due to their lower reactivity they have been least used in Morita-Baylis-Hillman (MBH) reaction and have been out of its vinylogus version Rauhut Currier (RC) reaction. Herein, use of acrylamide in RC reaction is being presented. Intramolecular RC reaction followed ...
DOI:
10.1016/j.tet.2017.08.002

94. Actinomadurone, a Polycyclic Tetrahydroxanthone from Actinomadura sp. BCC 35430

Author:
Taridaporn Bunyapaiboonsri; Seangaroon Yoiprommarat; Chanwit Suriyachadkun; Sumalee Supothina; Rungtiwa Chanthaket; Chanikul Chutrakul; Vanicha Vichai
Source:
Tetrahedron letters 2017 pp. -
ISSN:
0040-4039
Subject:
Actinomadura; Alternaria brassicicola; Colletotrichum capsici; Curvularia lunata; Glomerella cingulata; antifungal properties; chemical reactions; chemical structure; cytotoxicity; organic compounds; spectral analysis
Abstract:
... A polycyclic tetrahydroxanthone, actinomadurone, was isolated from the actinomycete Actinomadura sp. BCC 35430. Its structure was elucidated by extensive spectroscopic analyses. Actinomadurone showed antifungal activities against Curvularia lunata, Alternaria brassicicola, Colletotrichum capsici, and Colletotrichum gloeosporioides; and displayed cytotoxic activity against Vero cell lines. ...
DOI:
10.1016/j.tetlet.2017.07.008

95. Activation and Substitution of 1-Ferrocenylalkylamines with Allenones: Application to Three-Component Synthesis of 4-(1-Ferrocenylalkyl)pyrazoles

Author:
Chen Zhixiong; Han Lu; Tian Shi-Kai
Source:
Organic letters 2017 v.19 no.21 pp. 5852-5855
ISSN:
1523-7052
Subject:
air; ambient temperature; chemical reactions; chemical structure; extrusion; pyrazoles
Abstract:
... A one-pot, two-step three-component synthesis of 4-(1-ferrocenylalkyl)pyrazoles has been developed involving activation and substitution of 1-ferrocenylalkylamines with allenones under mild conditions. A range of 1-ferrocenylalkylamines reacted with allenones in the presence of dipicolinic acid at room temperature without extrusion of air and moisture, and the resulting crude products were treated ...
DOI:
10.1021/acs.orglett.7b02830

96. Activation of a Cryptic Gene Cluster in Lysobacter enzymogenes Reveals a Module/Domain Portable Mechanism of Nonribosomal Peptide Synthetases in the Biosynthesis of Pyrrolopyrazines

Author:
Li Shanren; Wu Xiuli; Zhang Limei; Shen Yuemao; Du Liangcheng
Source:
Organic letters 2017 v.19 no.19 pp. 5010-5013
ISSN:
1523-7052
Subject:
Lysobacter enzymogenes; biosynthesis; chemical reactions; chemical structure; gene silencing; ligases; multigene family; organic compounds
Abstract:
... Lysobacter are considered “peptide specialists”. However, many of the nonribosomal peptide synthetase genes are silent. Three new compounds were identified from L. enzymogenes upon activating the six-module-containing led cluster by the strong promoter PHSAF. Although ledD was the first gene under PHSAF control, the second gene ledE was expressed the highest. Targeted gene inactivation showed that ...
DOI:
10.1021/acs.orglett.7b01611
PubMed:
28898095
PubMed Central:
PMC5632221

97. Activation of cryptic phthoxazolin A production in Streptomyces avermitilis by the disruption of autoregulator-receptor homologue AvaR3

Author:
Dian Anggraini Suroto; Shigeru Kitani; Kiyoko T. Miyamoto; Yasuko Sakihama; Masayoshi Arai; Haruo Ikeda; Takuya Nihira
Source:
Journal of bioscience and bioengineering 2017 v.124 no.6 pp. 611-617
ISSN:
1389-1723
Subject:
Oomycetes; Streptomyces avermitilis; avermectins; bioactive compounds; bioassays; cell biology; cellulose; chemical structure; filipin; genetic engineering; multigene family; mutants; oligomycin; secondary metabolites; spectral analysis
Abstract:
... The genomes of actinomycetes encode many cryptic novel/useful bioactive compounds, but access to these cryptic secondary metabolites remains limited. Streptomyces avermitilis predominantly produces three polyketide antibiotics (avermectin, filipin, and oligomycin) but has the potential to produce more secondary metabolites based on the number of cryptic biosynthetic gene clusters. Here, we extensi ...
DOI:
10.1016/j.jbiosc.2017.06.014

98. Active sp3 C–H Bond Oxidation Initiated sp3–sp2 Consecutive C–H Functionalization of N-Arylglycine Amides: Construction of Isatins

Author:
Ji Honghe; Zhu Yingzu; Shao Yu; Liu Jing; Yuan Yu; Jia Xiaodong
Source:
Journal of organic chemistry 2017 v.82 no.18 pp. 9859-9865
ISSN:
1520-6904
Subject:
amides; aniline; carbon-hydrogen bond activation; cations; chemical bonding; chemical structure; cyclization reactions; organic chemistry; oxidation
Abstract:
... In the presence of catalytic triarylamine radical cation, an sp³–sp² consecutive C–H functionalization of N-arylglycine amides was achieved, providing a series of isatin derivatives in high yields. In this transformation, the initial aerobic oxidation of the relatively active sp³ C–H bonds triggered the following intramolecular cyclization, in which the aniline group was employed as a removable au ...
DOI:
10.1021/acs.joc.7b01480

99. Activity and stability spontaneously enhanced toward ethylene polymerization by employing 2‐(1‐(2,4‐dibenzhydrylnaphthylimino)ethyl)‐6‐(1‐(arylimino)ethyl) pyridyliron(II) dichlorides

Author:
Weizhen Zhao; Erlin Yue; Xinxin Wang; Wenhong Yang; Yan Chen; Xiang Hao; Xiaoping Cao; Wen‐Hua Sun
Source:
Journal of polymer science 2017 v.55 no.6 pp. 988-996
ISSN:
0887-624X
Subject:
X-ray diffraction; chemical structure; ethylene; iron; molecular weight; nuclear magnetic resonance spectroscopy; polyethylenes; polymerization; temperature; thermal stability
Abstract:
... A series of 2‐(1‐(2,4‐dibenzhydrylnaphthylimino)ethyl)‐6‐(1‐(arylimino)ethyl)pyridyliron(II) complexes (Fe1−Fe5) was synthesized and characterized. The molecular structure of the representative Fe2 was determined by single‐crystal X‐ray diffraction, revealing a distorted pseudo‐square‐pyramidal geometry around the iron center. On activation with either methylaluminoxane (MAO) or modified methylalu ...
DOI:
10.1002/pola.28459

100. Activity of continuous flow synthesized Pd-based nanocatalysts in the flow hydroconversion of furfural

Author:
Antonio J. Garcia-Olmo; Alfonso Yepez; Alina M. Balu; Pepijn Prinsen; Araceli Garcia; Audrey Maziere; Christophe Len; Rafael Luque
Source:
Tetrahedron 2017 pp. -
ISSN:
0040-4020
Subject:
alcohols; catalysts; chemical reactions; chemical structure; furfural; furfuryl alcohol; nanomaterials; palladium; temperature
Abstract:
... A number of synthesized supported Pd nanomaterials on aluminosilicate supports were investigated in the continuous flow hydroconversion of furfural to a range of furanic derivatives as compared to a commercial Pd/C catalyst. Excellent furfural conversions (>60%) and varying selectivities to products at mild temperatures (90 °C) could be obtained for most catalytic systems, with interesting selecti ...
DOI:
10.1016/j.tet.2017.02.056