PubAg

Main content area

You searched for: Subject "moieties" Remove constraint Subject: "moieties"
Start Over

Search

30,022  Search Results

« Previous | 1 - 20 of 30,022 |
Number of results to display per page

Search Results

1. NIS-TBHP promoted oxidative coupling of C[sbnd]N and C[sbnd]O bonds: A metal-free approach to polysubstituted oxazoles

Author:
Yang, Shengxiang; Yang, Yuzhu; Li, Fei; Liu, Xiaolan
Source:
Tetrahedron letters 2020 pp. 151846
ISSN:
0040-4039
Subject:
moieties,   etc   ; benzylamines; iodination; oxazoles;     Show all 4 Subjects
Abstract:
... A metal-free approach to polysubstituted oxazoles via the oxidative coupling of readily available benzylamines and 1,3-dicarbonyl derivatives in the presence of an external base has been developed. A variety of functional groups on both of the starting materials are tolerated using this method, affording the corresponding oxazoles in moderate to good yields. Iodination was proposed as the initiati ...
DOI:
10.1016/j.tetlet.2020.151846

2. Diastereoselective multicomponent phosphoramidate-aldehyde-dienophile (PAD) process for the synthesis of polysubstituted cyclohex-2-enyl-amine derivatives

Author:
Chabour, Ihssene; Nájera, Carmen; Sansano, José M.
Source:
Tetrahedron 2020 v.76 no.2 pp. 130801
ISSN:
0040-4020
Subject:
moieties,   etc   ; aldehydes; diastereoselectivity; hydrolysis;     Show all 4 Subjects
Abstract:
... The reaction of diethyl phosphoramidate, conjugated aldehydes and maleimides takes place in a multicomponent sequence named phosphoramidate-aldehyde-dienophile (PAD). The reaction affords a series of N-substituted phosphoramidates in good yields with α,β-unsaturated aldehydes bearing hydrogens at the γ-position. The reaction is diastereoselective and the effect of chiral information in the maleimi ...
DOI:
10.1016/j.tet.2019.130801

3. Synthesis of 2,3-disubstituted indoles from alkynylanilines and 2-chlorophenols using palladium–dihydroxyterphenylphosphine catalyst

Author:
Yamaguchi, Miyuki; Ogihara, Kota; Konishi, Hideyuki; Manabe, Kei
Source:
Tetrahedron letters 2020 v.61 no.21 pp. 151896
ISSN:
0040-4039
Subject:
moieties,   etc   ; catalysts; chemical reactions; indoles;     Show all 4 Subjects
Abstract:
... 2,3-Disubstituted indoles bearing 2-hydroxyphenyl moieties at their C3 positions were synthesized from readily available 2-chlorophenols and alkynylanilines via aminopalladation/reductive elimination using Pd–dihydroxyterphenylphosphine catalyst. The catalyst accelerates the introduction of the 2-hydroxyphenyl group at the C3 position of the indole. ...
DOI:
10.1016/j.tetlet.2020.151896

4. The synthesis of isoxazolo[2,3-c]quinazolines via a cycloaddition of quinazoline-3-oxides and acrylates

Author:
Yin, Zhijian; Li, Xinyi; Deng, Zhihong; Yang, Qin; Peng, Yiyuan
Source:
Tetrahedron letters 2020 pp. 151818
ISSN:
0040-4039
Subject:
moieties,   etc   ; acrylates; cycloaddition reactions; dioxane;     Show all 4 Subjects
Abstract:
... A variety of isoxazolo[2,3-c]quinazolines were synthesized via a [3+2] cycloaddition of quinazoline-3-oxides with acrylates. The reaction exhibits a broad substrate scope and good functional group tolerance. The corresponding isoxazolo[2,3-c]quinazolines can be obtained in good to excellent yields in 1,4-dioxane. ...
DOI:
10.1016/j.tetlet.2020.151818

5. Transition metal-free direct C[sbnd]H trifluoromethyltion of (hetero)arenes with Togni’s reagent

Author:
Chen, Xiaoyu; Ding, Licheng; Li, Linlin; Li, Jingya; Zou, Dapeng; Wu, Yangjie; Wu, Yusheng
Source:
Tetrahedron letters 2020 v.61 no.9 pp. 151538
ISSN:
0040-4039
Subject:
moieties,   etc   ; aromatic hydrocarbons; chemical reactions;     Show all 3 Subjects
Abstract:
... A new transition-metal-free direct CH trifluoromethylation reaction of (hetero)arenes with Togni’s reagent was developed. This transformation proceeded smoothly under mild conditions and exhibited good tolerance of many synthetically relevant functional groups. It provided an alternative approach for the synthesis of trifluoromethylated (hetero)arenes. ...
DOI:
10.1016/j.tetlet.2019.151538

6. π-Extension, Selenium Incorporation, and Trimerization: “Three in One” for Efficient Perylene Diimide Oligomer-Based Organic Solar Cells

Author:
Wang, Keke; Xia, Ping; Wang, Kangwei; You, Xiaoxiao; Wu, Mingliang; Huang, Huaxi; Wu, Di; Xia, Jianlong
Source:
ACS applied materials & interfaces 2020 v.12 no.8 pp. 9528-9536
ISSN:
1944-8252
Subject:
moieties,   etc   ; blades; selenium; solar cells;     Show all 4 Subjects
Abstract:
... Perylene diimide (PDI) and the vinylene-bridged helical PDI oligomers are versatile building blocks for constructing nonfullerene acceptors (NFAs). In this contribution, a benzene-cored star-shaped NFA, namely, TPDI2-Se, was designed and synthesized for organic solar cells (OSCs). The NFA with smaller π-conjugated blades, namely, TPDI-Se, was synthesized for comparison. Using the commercially avai ...
DOI:
10.1021/acsami.9b21929

7. Transition-metal-free direct cross-dehydrogenative coupling reactions of quinolinones with ethers

Author:
Wang, Gang; Wang, Jun-Tao; Zhao, Bing; Chen, Huan; Zhang, Pan-Ke; Han, Shu-Lei
Source:
Tetrahedron letters 2020 v.61 no.4 pp. 151426
ISSN:
0040-4039
Subject:
moieties,   etc   ; chemical reactions; ethers; quinolones;     Show all 4 Subjects
Abstract:
... An efficient and convenient transition-metal-free strategy for the synthesis of 3-alkyl quinolinones via the radical cross-dehydrogenative coupling reaction of quinolinones with ethers was developed with moderate to good yields. This strategy using a straightforward route exhibited broad substrate scope, good functional group tolerance, and high atom economy, to afford various important quinolinon ...
DOI:
10.1016/j.tetlet.2019.151426

8. An efficient pseudo-seven component reaction for the synthesis of fully-substituted furans containing pseudopeptide based on the union of multicomponent reactions

Author:
Nazeri, Mohammad Taghi; Mohammadian, Reza; Farhid, Hassan; Shaabani, Ahmad; Notash, Behrouz
Source:
Tetrahedron letters 2020 v.61 no.3 pp. 151408
ISSN:
0040-4039
Subject:
moieties,   etc   ; chemical reactions; energy; furans;     Show all 4 Subjects
Abstract:
... An atom, step, and energy economic approach based on the union of multicomponent reactions (MCRs) is reported to create higher-order MCRs with unique possibilities for complexity generation of fully-substituted furan derivatives containing pseudopeptidic groups. The unprecedented seven component reaction resulting from implementation of this strategy, provides very complex and valuable scaffolds w ...
DOI:
10.1016/j.tetlet.2019.151408

9. Structurally Isomerized Bis-Biphenyl Moieties Embedded in Hexaphyrin(3.1.1.3.1.1) and Octaphyrin(1.1.1.0.1.1.1.0)

Author:
Chitranshi, Sangya; Das, Mainak; Adinarayana, B.; Cha, Won-Young; Kim, Dongho; Srinivasan, A.
Source:
Organic letters 2020 v.22 no.3 pp. 1081-1085
ISSN:
1523-7052
Subject:
moieties,   etc   ; biphenyl; constitutional isomers; isomerization;     Show all 4 Subjects
Abstract:
... An o-p-biphenyl moiety-incorporated 32π hexaphyrin(3.1.1.3.1.1) is successfully achieved. Replacing ortho with meta connectivity in the biphenyl unit of hexaphyrin leads to the formation of its structural isomer, octaphyrin(1.1.1.0.1.1.1.0). Spectral and structural analyses reveal the lack of planarity in hexaphyrin and the presence of an m-arene unit in octaphyrin, thus affording nonaromatic char ...
DOI:
10.1021/acs.orglett.9b04614

10. Copper-catalyzed synthesis of 2-aminopyridylbenzoxazoles via domino reactions of intermolecular N-arylation and intramolecular O-arylation

Author:
Lu, Ju-You
Source:
RSC advances 2019 v.9 no.24 pp. 13414-13417
ISSN:
2046-2069
Subject:
moieties
Abstract:
... A simple and general approach to nitrogen-containing heterocycles via copper-catalyzed domino reaction has been developed, and the corresponding 2-aminopyridylbenzoxazole derivatives were obtained in good to excellent yields using the readily available starting materials. This method possesses unique step economy features, and is of high tolerance towards various functional groups in the substrate ...
DOI:
10.1039/c9ra01908a

11. Carbamate as an accelerating group in intermolecular Pauson-Khand reaction

Author:
Asano, Shota; Itto-Nakama, Kaori; Arimoto, Hirokazu
Source:
Tetrahedron letters 2020 v.61 no.24 pp. 151974
ISSN:
0040-4039
Subject:
moieties,   etc   ; chemical reactions; organic compounds; regioselectivity;     Show all 4 Subjects
Abstract:
... The Pauson-Khand reaction (PKR) is a powerful means for the construction of cyclopentenones. However, its applications have been limited to the intramolecular version of this reaction because poor yield and regioselectivity are often the major problems in intermolecular PKR. Here we describe that a carbamate moiety in alkene substrate accelerates this intermolecular PKR. The reaction of N-4-dimeth ...
DOI:
10.1016/j.tetlet.2020.151974

12. Scandium-catalyzed Michael addition of quinazolinones and vinylazaarenes

Author:
Zhang, Zhiguang; Dai, Siwei; Li, Ling; Jia, Chenyu; Zhang, Yong; Li, Hao
Source:
Tetrahedron letters 2020 v.61 no.23 pp. 151926
ISSN:
0040-4039
Subject:
moieties,   etc   ; catalytic activity; chemical reactions; organic compounds;     Show all 4 Subjects
Abstract:
... We described a novel scandium-catalyzed selective Michael addition of quinazolinones and vinylazaarenes. The protocol proceeds smoothly to give diverse quinazolinone derivatives in moderate to excellent yields. The high practicality of this protocol was proved by excellent chemo selectivity and broad substrate and functional group compatibility. ...
DOI:
10.1016/j.tetlet.2020.151926

13. Trifluoromethylthiolation and trifluoromethanesulfonylation of β,γ-unsaturated hydrazones

Author:
Xiao, Hongqing; Meng, Weidong; Xu, Xiu-Hua; Huang, Yangen
Source:
Tetrahedron letters 2020 v.61 no.23 pp. 151927
ISSN:
0040-4039
Subject:
moieties,   etc   ; chemical reactions; hydrazones; pyrazoles; silver; sodium;     Show all 6 Subjects
Abstract:
... The trifluoromethylthiolation and trifluoromethanesulfonylation of β,γ-unsaturated hydrazones was accomplished with silver(I) trifluoromethanethiolate (AgSCF₃) as a CF₃S source and sodium trifluoromethylsulfinate (CF₃SO₂Na) as a CF₃SO₂ source, respectively. These general methods for the preparation of dihydropyrazoles containing CF₃S or CF₃SO₂ groups were characterized by mild reaction conditions ...
DOI:
10.1016/j.tetlet.2020.151927

14. A novel synthesis of diversely functionalized 1,2,4-triones through the homo- and cross-coupling reactions of β-keto sulfoxonium ylides

Author:
Chen, Xi; Wang, Muhua; Zhang, Xinying; Fan, Xuesen
Source:
Tetrahedron letters 2020 v.61 no.22 pp. 151912
ISSN:
0040-4039
Subject:
moieties,   etc   ; aldehydes; copper; cross-coupling reactions;     Show all 4 Subjects
Abstract:
... A novel synthesis of functionalized 1,2,4-triones via an oxidative homo-coupling of β-keto sulfoxonium ylides is presented. Preliminary mechanistic study reveals that the formation of the 1,2,4-trione product involves the in situ generation of an α-keto aldehyde intermediate via Cu(II)-promoted oxidative decomposition of β-keto sulfoxonium ylide followed by its coupling with the second molecule of ...
DOI:
10.1016/j.tetlet.2020.151912

15. Facile access to fluoroalkylated 2-aminopyridines by Cu-catalyzed [3 + 3] couplings of oxime esters with β-CF3 acrylonitrile

Author:
Li, Xueyan; Yu, Yanjiang; Qi, Ruobing; Bai, Dachang
Source:
Tetrahedron letters 2020 v.61 no.20 pp. 151858
ISSN:
0040-4039
Subject:
moieties,   etc   ; catalytic activity; chemical reactions; esters; regioselectivity;     Show all 5 Subjects
Abstract:
... Copper catalyzed the [3 + 3] coupling of the oxime esters with β-CF₃-acrylonitrile toward divergent fluoroalkyl-substituted 2-aminopyridines was described. This redox-neutral coupling conditions with the acrylonitrile affording the trifluoromethylated 2-aminopyridines, respectively, under the reductive conditions, difluoromethylated 2-aminopyridines were obtained. The reactions occurred under mild ...
DOI:
10.1016/j.tetlet.2020.151858

16. Graphitic carbon nitride nanodots: electronic structure and its influence factors

Author:
Feng, Jin; Zhang, Dapeng; Li, Jiawei; Bi, Siwei; Ma, Yuchen
Source:
Journal of materials science 2020 v.55 no.13 pp. 5488-5498
ISSN:
0022-2461
Subject:
moieties,   etc   ; carbon nitride; graphene; nanotechnology; optical properties;     Show all 5 Subjects
Abstract:
... The graphitic carbon nitride (g-C₃N₄) nanodots (CN-dots) exhibit properties different from those of g-C₃N₄ crystal. However, the electronic structure of g-C₃N₄ nanodots, which determines their properties intrinsically, has not been explored comprehensively. Herein, the many-body Green’s function theory is used to analyze the electronic and optical properties of CN-dots; and the effects of size, sh ...
DOI:
10.1007/s10853-020-04396-x

17. The Pathway Less Traveled: Engineering Biosynthesis of Nonstandard Functional Groups

Author:
Sulzbach, Morgan; Kunjapur, Aditya M.
Source:
Trends in biotechnology 2020 v.38 no.5 pp. 532-545
ISSN:
0167-7799
Subject:
moieties,   etc   ; aldehydes; alkynes; biosynthesis; hydrazine; metabolic engineering;     Show all 6 Subjects
Abstract:
... The field of metabolic engineering has achieved biochemical routes for conversion of renewable inputs to structurally diverse chemicals, but these products contain a limited number of chemical functional groups. In this review, we provide an overview of the progression of uncommon or ‘nonstandard’ functional groups from the elucidation of their biosynthetic machinery to the pathway optimization fr ...
DOI:
10.1016/j.tibtech.2019.12.014

18. Understanding the chemical structure of carbon edge sites by using deuterium-labeled temperature-programmed desorption technique

Author:
Ishii, Takafumi; Ozaki, Jun-ichi
Source:
Carbon 2020 v.161 pp. 343-349
ISSN:
0008-6223
Subject:
moieties,   etc   ; activated carbon; desorption; deuterium; deuterium oxide;     Show all 5 Subjects
Abstract:
... A deuterium-labeled temperature-programmed desorption (TPD) technique was developed to accurately characterize functional groups on the surface of carbon-based materials. After the protic hydrogen of the functional groups on activated carbons was substituted by deuterium, TPD analysis revealed the desorption of deuterium compounds (D₂O, DHO, D₂, DH). The functional groups were estimated from the p ...
DOI:
10.1016/j.carbon.2020.01.079

19. Convergent Route to β-Amino Acids and to β-Heteroarylethylamines: An Unexpected Vinylation Reaction

Author:
Chen, Xuan; Zard, Samir Z.
Source:
Organic letters 2020 v.22 no.9 pp. 3628-3632
ISSN:
1523-7052
Subject:
moieties,   etc   ; amines; amino acids; decarboxylation; propionic acid;     Show all 5 Subjects
Abstract:
... Various protected β²-amino acids can be prepared by radical addition of β-phthalimido-α-xanthyl propionic acid, both as the free acid or as the ethyl ester. Successive radical additions provide access to more complex structures. In the case of the free acid, addition to certain heteroaromatics leads directly to β-heteroarylethylamines through spontaneous decarboxylation of the intermediate adduct. ...
DOI:
10.1021/acs.orglett.0c01087

20. Systematic strategy utilizing 1,5-lactamization for the synthesis of the trisialylated galactose unit of c-series gangliosides

Author:
Shirasaki, Junya; Tanaka, Hide-Nori; Konishi, Miku; Hirose, Yuya; Imamura, Akihiro; Ishida, Hideharu; Kiso, Makoto; Ando, Hiromune
Source:
Tetrahedron letters 2020 v.61 no.16 pp. 151759
ISSN:
0040-4039
Subject:
moieties,   etc   ; chemical reactions; galactose; gangliosides; sialic acid;     Show all 5 Subjects
Abstract:
... c-Series gangliosides have important biological roles, but their synthesis is challenging, and natural sources are heterogenous and difficult to purify, so synthetic routes to these compounds are required. Here, a synthetic strategy utilizing 1,5-lactamization to construct the trisialylated galactose framework of c-series gangliosides in complete stereopurity is presented. The transformation enabl ...
DOI:
10.1016/j.tetlet.2020.151759