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You searched for: Journal name Organic letters Remove constraint Journal name: Organic letters Publication year rev 7981-2019 Remove constraint Publication year rev: 7981-2019 Source 2019 v.21 no.24 Remove constraint Source: 2019 v.21 no.24
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1. (3 + 1) Annulation/Rearrangement Cascade of C,N-Cyclic Azomethine Imines and 3-Chlorooxindoles: Construction of Hexahydroindeno[2,1-c]pyrazole Spirooxindole Frameworks

Author:
Peng-Fei Zheng; Rong Zeng; Kun Jiang; Hong-Wei Li; Ying Ye; Chao Mu; Li Shuai; Qin Ouyang; Ying-Chun Chen
Source:
Organic letters 2019 v.21 no.24 pp. 10052-10056
ISSN:
1523-7052
Subject:
ambient temperature; chemical reactions; chemical structure; imines; pyrazoles
Abstract:
... The Brønsted base promoted (3 + 1) annulation reaction of C,N-cyclic azomethine imines and 3-chlorooxindoles was investigated, finally delivering complex hexahydroindeno[2,1-c] pyrazoles incorporating a spirocyclic oxindole motif after an unexpected rearrangement process. The asymmetric version of this new transformation could be accomplished, but slow racemization of the chiral product was observ ...
DOI:
10.1021/acs.orglett.9b03996

2. 2-(Dibenzylamino)butane-1,4-dithiol (DABDT), a Friendly Disulfide-Reducing Reagent Compatible with a Broad Range of Solvents

Author:
Sinenhlanhla N. Mthembu; Anamika Sharma; Fernando Albericio; Beatriz G. de la Torre
Source:
Organic letters 2019 v.21 no.24 pp. 10111-10114
ISSN:
1523-7052
Subject:
aspartic acid; chemical reactions; chemical structure; solvents; thiols
Abstract:
... Disulfide-reducing agents play a crucial role in bioconjugate chemistry. Herein, we describe the synthesis of a new disulfide-reducing agent [2-(dibenzylamino)butane-1,4-dithiol (DABDT)] that is conveniently prepared from inexpensive aspartic acid. Being nonmalodorous and highly soluble in a broad range of solvents, DABDT is user-friendly. We have demonstrated its performance both in solution and ...
DOI:
10.1021/acs.orglett.9b04106

3. A Fast Track to Indoles and Annulated Indoles through ortho- vs ipso-Amination of Aryl Halides

Author:
Farnaz Jafarpour; Mehran Ghasemi; Farid Mohaghegh; Sara Asgari; Azizollah Habibi
Source:
Organic letters 2019 v.21 no.24 pp. 10143-10148
ISSN:
1523-7052
Subject:
alkynes; amination; amines; carbon-hydrogen bond activation; catalytic activity; chemical bonding; chemical structure; indoles; organic halogen compounds; palladium
Abstract:
... A complementary site selective ortho- vs ipso-amination of aryl halides using non-electrophilic amine sources for construction of indole scaffolds is reported. A palladium-catalyzed alkyne insertion/C–H activation/palladacycle amination via merger of three easily diversified components including iodoarenes, alkynes, and amines delivers indoles with different substitution patterns even in gram scal ...
DOI:
10.1021/acs.orglett.9b04202

4. A Strategy for the Synthesis of Sulfonamides on DNA

Author:
Wei Liu; Wei Deng; Saisai Sun; Chunyan Yu; Xubo Su; Aliang Wu; Youlang Yuan; Zhonglin Ma; Ke Li; Hongfang Yang; Xuanjia Peng; Justin Dietrich
Source:
Organic letters 2019 v.21 no.24 pp. 9909-9913
ISSN:
1523-7052
Subject:
DNA; acids; amines; chemical reactions; chemical structure; iodine; sodium; sulfonamides
Abstract:
... An efficient method is reported to synthesize sulfonamides on DNA from sulfinic acids or sodium sulfinates and amines in the presence of iodine under mild conditions. This method demonstrates a major expansion of scope of sulfonamide formation on DNA through the utilization of a novel sodium carbonate–sodium sulfinate bifunctional reagent class. ...
DOI:
10.1021/acs.orglett.9b03843

5. Aqueous tert-Butyl Hydroperoxide Mediated Regioselective Ring-Opening Reactions of Spiro-aziridine-epoxy Oxindoles: Synthesis of 3-Peroxy-3-substituted Oxindoles and Their Acid-Mediated Rearrangement

Author:
Saumen Hajra; Atanu Hazra; SK Abu Saleh; Ananda Shankar Mondal
Source:
Organic letters 2019 v.21 no.24 pp. 10154-10158
ISSN:
1523-7052
Subject:
chemical reactions; chemical structure; ethyleneimine; regioselectivity
Abstract:
... A highly efficient regioselective C3-peroxylation of spiro-aziridine and spiro-epoxy oxindoles has been developed with commercially available 70% aqueous tert-butyl hydroperoxide under solvent-free and metal/catalyst-free conditions. The protocol provides an easy access of 3-peroxyoxindoles, which undergo acid-mediated rearrangement to afford unprecedented 2-hydroxy-2-substituted-2H-benzo[b][1,4]o ...
DOI:
10.1021/acs.orglett.9b04229

6. Cobalt-Catalyzed Oxidative Annulation of Benzothiophene-[b]-1,1-dioxide through Diastereoselective Double C–H Activation

Author:
Subban Kathiravan; Ian A. Nicholls
Source:
Organic letters 2019 v.21 no.24 pp. 9806-9811
ISSN:
1523-7052
Subject:
carbon-hydrogen bond activation; catalytic activity; chemical reactions; chemical structure; cobalt; diastereoselectivity; organic compounds
Abstract:
... The use of inexpensive base metal catalysis to perform C–H activation is an active field of research in organic synthesis. Described herein is a sustainable cobalt-catalyzed diastereoselective oxidative annulation/double C–H activation of benzothiophene-[b]-1,1-dioxide with aminoquinolinamides under mild reaction conditions for the synthesis of annulated benzothiophenes. ...
DOI:
10.1021/acs.orglett.9b03158

7. Continuous Flow Synthesis of Terminal Epoxides from Ketones Using in Situ Generated Bromomethyl Lithium

Author:
Timo von Keutz; David Cantillo; C. Oliver Kappe
Source:
Organic letters 2019 v.21 no.24 pp. 10094-10098
ISSN:
1523-7052
Subject:
chemical reactions; chemical structure; drugs; epoxides; fluconazole; ketones; lithium
Abstract:
... A scalable procedure for the direct preparation of epoxides from ketones has been developed. The method is based on the carefully controlled generation of (bromomethyl)lithium (LiCH₂Br) from inexpensive CH₂Br₂ and MeLi in a continuous flow reactor. The reaction has shown excellent selectivity for a variety of substrates, including α-chloroketones, which typically fail under classic Corey–Chaykovsk ...
DOI:
10.1021/acs.orglett.9b04072

8. Copper-Mediated Direct Cyanation of Heteroarene and Arene C–H Bonds by the Combination of Ammonium and DMF

Author:
Shengbo Xu; Jiangang Teng; Jin-Tao Yu; Song Sun; Jiang Cheng
Source:
Organic letters 2019 v.21 no.24 pp. 9919-9923
ISSN:
1523-7052
Subject:
ammonium; aromatic hydrocarbons; chemical bonding; chemical reactions; indoles; moieties; pyrroles
Abstract:
... A copper-mediated cyanation of heteroarene and arene C–H bonds has been developed, where ammonium iodide and DMF served as a safe cyanating combination. This procedure shows a broad substrate scope, allowing the facile access of 2-cyano indole, 1-cyano carbazole, 2-cyano pyrrole, and 2-cyano 1-pyridinyl benzene in high yields with good functional group tolerance. ...
DOI:
10.1021/acs.orglett.9b03861

9. C–H Functionalization Approach for the Synthesis of Chiral C₂-Symmetric 1,5-Cyclooctadiene Ligands

Author:
Bowen Zhang; Michael R. Hollerbach; Simon B. Blakey; Huw M. L. Davies
Source:
Organic letters 2019 v.21 no.24 pp. 9864-9868
ISSN:
1523-7052
Subject:
arylation; carbon-hydrogen bond activation; catalytic activity; chemical structure; diastereoselectivity; enantioselectivity; ligands; organic compounds; rhodium
Abstract:
... Chiral cyclooctadiene (COD) derivatives are readily prepared by rhodium-catalyzed allylic C–H functionalization of COD. Either mono- or difunctionalization of COD is possible generating the products in high yield, diastereoselectivity and enantioselectivity. The double C–H functionalization generates C₂-symmetric COD derivatives with four new stereogenic centers in >99% ee, which can be readily co ...
DOI:
10.1021/acs.orglett.9b03764

10. Diastereoselective Desymmetrization of p-Quinamines through Regioselective Ring Opening of Epoxides and Aziridines

Author:
Sandip B. Jadhav; Rambabu Chegondi
Source:
Organic letters 2019 v.21 no.24 pp. 10115-10119
ISSN:
1523-7052
Subject:
aziridines; carbon; chemical structure; cyclization reactions; diastereoselectivity; epoxides; morpholines; piperazines; regioselectivity
Abstract:
... A highly diastereoselective desymmetrization of p-quinamines via regioselective ring opening of epoxides and aziridines under mild conditions has been developed. A chairlike six-membered transition state with minimized 1,3-diaxial interactions explains the relative stereoselectivity of the cyclization reaction. This transition-metal free [3 + 3] annulation reaction provides rapid access to fused b ...
DOI:
10.1021/acs.orglett.9b04110

11. Electrochemically Enabled Double C–H Activation of Amides: Chemoselective Synthesis of Polycyclic Isoquinolinones

Author:
Zi-Qiang Wang; Cheng Hou; Yuan-Fang Zhong; Yu-Xuan Lu; Zu-Yu Mo; Ying-Ming Pan; Hai-Tao Tang
Source:
Organic letters 2019 v.21 no.24 pp. 9841-9845
ISSN:
1523-7052
Subject:
alkynes; amides; carbon-hydrogen bond activation; catalysts; chemical structure; chemoselectivity; dehydrogenation; electricity; electrochemistry; oxidants; regioselectivity; ruthenium
Abstract:
... We developed an electrochemically enabled dehydrogenative annulation reaction of amides and alkynes for the synthesis of antitumor polycyclic isoquinolinones through a double C–H activation route. No external oxidant is required in this reaction, and electricity is used for Ru catalyst circulation. The most remarkable feature of this reaction is the effective improvement of product regioselectivit ...
DOI:
10.1021/acs.orglett.9b03682

12. Epimerization of an Ascaroside-Type Glycolipid Downstream of the Canonical β-Oxidation Cycle in the Nematode Caenorhabditis nigoni

Author:
Célia P. Bergame; Chuanfu Dong; Sylvain Sutour; Stephan H. von Reuß
Source:
Organic letters 2019 v.21 no.24 pp. 9889-9892
ISSN:
1523-7052
Subject:
Caenorhabditis; beta oxidation; chemical reactions; chemical structure; glycolipids; nuclear magnetic resonance spectroscopy; organic compounds; tandem mass spectrometry
Abstract:
... A species-specific ascaroside-type glycolipid was identified in the nematode Caenorhabditis nigoni using HPLC-ESI-(−)-MS/MS precursor ion scanning, HR-MS/MS, and NMR techniques. Its structure containing an l-3,6-dideoxy-lyxo-hexose unit was established by total synthesis. The identification of this novel 4-epi-ascaroside (caenorhabdoside) in C. nigoni along with the previous identification of 2-ep ...
DOI:
10.1021/acs.orglett.9b03808

13. Formal Deoxygenative Hydrogenation of Lactams Using PNᴴP-Pincer Ruthenium Complexes under Nonacidic Conditions

Author:
Osamu Ogata; Hideki Nara; Kazuhiko Matsumura; Yoshihito Kayaki
Source:
Organic letters 2019 v.21 no.24 pp. 9954-9959
ISSN:
1523-7052
Subject:
alcohols; catalysts; chemical structure; dehydrogenation; hydrogen; hydrogenation; imines; lactams; primary amines; ruthenium; secondary amines; temperature
Abstract:
... A formal deoxygenative hydrogenation of amides to amines with RuCl₂(NHC)(PNᴴP) (NHC = 1,3-dimethylimizadol-2-ylidene, PNᴴP = bis(2-diphenylphosphinoethyl)amine) is described. Various secondary amides, especially NH-lactams, are reduced with H₂ (3.0–5.0 MPa) to amines at a temperature range of 120–150 °C with 1.0–2.0 mol % of PNᴴP–Ru catalysts in the presence of Cs₂CO₃. This process consists of (1) ...
DOI:
10.1021/acs.orglett.9b03878

14. Iron-Catalyzed Enantioselective Intramolecular Inverse Electron-Demand Hetero Diels–Alder Reactions: An Access to Bicyclic Dihydropyran Derivatives

Author:
Jimmy Lauberteaux; Aurélien Lebrun; Arie van der Lee; Marc Mauduit; Renata Marcia de Figueiredo; Jean-Marc Campagne
Source:
Organic letters 2019 v.21 no.24 pp. 10007-10012
ISSN:
1523-7052
Subject:
catalytic activity; cycloaddition reactions; enantioselectivity; iron; ligands; moieties; organic compounds
Abstract:
... A highly enantioselective iron-catalyzed Intramolecular Inverse Electron-Demand Hetero Diels–Alder (IIEDHDA) reaction is reported. By using a chiral semicorrin ligand in the presence of 2,6-lutidine, good isolated yields and excellent enantioselectivities were observed (up to 96% ee). Thanks to the versatile postfunctionalization of the acyl-imidazole moiety, this methodology represents a unique e ...
DOI:
10.1021/acs.orglett.9b03752

15. Light-Enabled Enantiodivergence: Stereospecific Reduction of Activated Alkenes Using a Single Organocatalyst Enantiomer

Author:
Theresa Hostmann; John J. Molloy; Kathrin Bussmann; Ryan Gilmour
Source:
Organic letters 2019 v.21 no.24 pp. 10164-10168
ISSN:
1523-7052
Subject:
alkenes; catalytic activity; chemical reactions; drugs; enantiomers; organocatalysts; stereospecificity; thiourea; weight loss
Abstract:
... Light-enabled enantiodivergence is demonstrated in which the alkene substrate configuration is manipulated (E → Z) prior to organocatalytic reduction with a chiral thiourea and Hantzsch ester. This allows stereodivergent reduction to be regulated at the substrate level with high fidelity and mitigates the need for a second, enantiomeric catalyst (up to 93:07 and 95:5 er). The synthetic utility of ...
DOI:
10.1021/acs.orglett.9b04263

16. Organic Photoredox-Catalyzed Decarboxylative Trifluoromethylselenolation of Aliphatic Carboxylic Acids with [Me₄N][SeCF₃]

Author:
Qiu-Yan Han; Kai-Li Tan; Hao-Nan Wang; Cheng-Pan Zhang
Source:
Organic letters 2019 v.21 no.24 pp. 10013-10017
ISSN:
1523-7052
Subject:
Lewis bases; ambient temperature; carboxylic acids; catalytic activity; decarboxylation; drugs; moieties; photocatalysts
Abstract:
... Oxidative decarboxylation/trifluoromethylselenolation of primary, secondary, and tertiary aliphatic carboxylic acids with the nucleophilic [Me₄N][SeCF₃] salt and an organic photocatalyst is described. The reaction proceeds smoothly at room temperature under transition-metal-free conditions and affords the corresponding trifluoromethylselenolated products in good yields. Advantages of the method in ...
DOI:
10.1021/acs.orglett.9b03941

17. Organophotocatalytic Arene Functionalization: C–C and C–B Bond Formation

Author:
Da Seul Lee; Chung Soo Kim; Naila Iqbal; Gyeong Su Park; Kyung-sun Son; Eun Jin Cho
Source:
Organic letters 2019 v.21 no.24 pp. 9950-9953
ISSN:
1523-7052
Subject:
aromatic hydrocarbons; boron compounds; catalytic activity; chemical bonding; chemical reactions; chemical structure; organic halogen compounds
Abstract:
... Organophotocatalytic C–C and C–B bond formation reactions of aryl halides have been developed in the presence of an organophotosensitizer, 3,7-di([1,1′-biphenyl]-4-yl)-10-(4-(trifluoromethyl)phenyl)-10H-phenoxazine that has highly negative reduction potential at its photoexcited state. The developed reaction conditions are mild and allow the intermolecular C–C bond formation of the generated aryl ...
DOI:
10.1021/acs.orglett.9b03877

18. Palladium-Catalyzed Domino Heck/C–H Activation/Decarboxylation: A Rapid Entry to Fused Isoquinolinediones and Isoquinolinones

Author:
Xiai Luo; Liwei Zhou; Haiyan Lu; Guobo Deng; Yun Liang; Chunming Yang; Yuan Yang
Source:
Organic letters 2019 v.21 no.24 pp. 9960-9964
ISSN:
1523-7052
Subject:
benzoic acids; carbon-hydrogen bond activation; catalytic activity; chemical structure; cyclization reactions; decarboxylation; organoiodine compounds; palladium; regioselectivity
Abstract:
... A new palladium-catalyzed tandem cyclization of various alkene-tethered aryl iodides has been presented. In this protocol, o-bromobenzoic acids are employed as coupling parters to achieve the insertion of aromatic rings by the cleavage of C(sp²)–Br and decarboxylation, thus assembling various dibenzoisoquinolinediones and dibenzoisoquinolinones. In addition, a seven-membered ring can be constructe ...
DOI:
10.1021/acs.orglett.9b03883

19. Para-Selective Dehydrogenative Phenothiazination of Hydroquinolines and Indolines

Author:
Pooja Y. Vemuri; Yongchao Wang; Frederic W. Patureau
Source:
Organic letters 2019 v.21 no.24 pp. 9856-9859
ISSN:
1523-7052
Subject:
chemical bonding; chemical structure; dehydrogenation; drugs; phenothiazines; quinolines
Abstract:
... Nitrogen-containing heterocyclic systems, such as hydroquinolines, indolines, and phenothiazines, are prevalent in pharmaceuticals, natural products, and organic materials. It is therefore important to develop novel reaction strategies that give access to such biologically relevant scaffolds. This report demonstrates a novel robust, para-selective C–N bond formation between phenothiazines and quin ...
DOI:
10.1021/acs.orglett.9b03729

20. Pd(0)-Catalyzed Intramolecular “Ylide-Ullmann-Type” Cyclization of Carbonyl-Stabilized Phosphonium Ylides and Access to Phosphachromones by Exocyclic P–C Cleavage

Author:
Shuangshuang Xu; Haiyang Huang; Zeen Yan; Qiang Xiao
Source:
Organic letters 2019 v.21 no.24 pp. 10018-10022
ISSN:
1523-7052
Subject:
catalytic activity; chemical bonding; chemoselectivity; cleavage (chemistry); hydrolysis; moieties; organobromine compounds; palladium; salts
Abstract:
... An unprecedented palladium-catalyzed intramolecular Ullmann-type cyclization of carbonyl-stabilized phosphonium ylides with aryl bromides was successfully developed. Furthermore, a base-promoted chemoselective hydrolysis of exocyclic P–C bond of the corresponding phosphonium salts delivered various phosphachromones. Excellent selectivity and high efficiency and good functional group tolerance were ...
DOI:
10.1021/acs.orglett.9b03948