PubAg

Main content area

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

Search

14,390  Search Results

« Previous | 1 - 20 of 14,390 |
Number of results to display per page

Search Results

1. Access to Highly Functionalized Indanes from Arynes and α,γ-Diketo Esters

Author:
Hu, Wanyao; Zhang, Cong; Huang, Jie; Guo, Yingying; Fu, Zhenqian; Huang, Wei
Source:
Organic letters 2019 v.21 no.4 pp. 941-945
ISSN:
1523-7052
Subject:
moieties,   etc   ; chemical reactions; esters;     Show all 3 Subjects
Abstract:
... An unprecedented method for the synthesis of highly functionalized indanes from arynes and α,γ-diketo esters is described. Importantly, mild and nearly pH-neutral conditions ensure excellent functional group tolerance. Theoretical studies indicated that the reaction proceeds through a benzocyclobutane intermediate. ...
DOI:
10.1021/acs.orglett.8b03919

2. Polysaccharides for tissue engineering: Current landscape and future prospects

Author:
Tchobanian, Armen; Van Oosterwyck, Hans; Fardim, Pedro
Source:
Carbohydrate polymers 2019 v.205 pp. 601-625
ISSN:
0144-8617
Subject:
moieties,   etc   ; landscapes; polysaccharides; tissue engineering;     Show all 4 Subjects
Abstract:
... Biological studies on the importance of carbohydrate moieties in tissue engineering have incited a growing interest in the application of polysaccharides as scaffolds over the past two decades. This review provides a perspective of the recent approaches in developing polysaccharide scaffolds, with a focus on their chemical modification, structural versatility, and biological applicability. The cur ...
DOI:
10.1016/j.carbpol.2018.10.039

3. Effect of bond orbital interactions on the conformational stabilities of 1,2-difluoroethane and 2,3-difluorobutanes

Author:
Hayashi, Nobuyuki; Ujihara, Tomomi; Ikeda, Hirotaka
Source:
Tetrahedron 2019 v.75 no.4 pp. 527-532
ISSN:
0040-4020
Subject:
moieties,   etc   ; chemical reactions; organic compounds;     Show all 3 Subjects
Abstract:
... Several hypotheses have been proposed to explain the origin of the conformational stabilities of 1,2-difluoroalkanes, for which bond orbital interactions are an important factor. However, there is a limit to the effectiveness of the traditional approach focusing on only the antiperiplanar interactions between bonding and antibonding orbitals such as σC–H/σC–F*, σC–C/σC–F*, and σC–F/σC–F*, which ca ...
DOI:
10.1016/j.tet.2018.12.029

4. Direct coupling of haloquinolines and sulfonyl chlorides leading to sulfonylated quinolines in water

Author:
Bao, Pengli; Wang, Leilei; Liu, Qishun; Yang, Daoshan; Wang, Hua; Zhao, Xiaohui; Yue, Huilan; Wei, Wei
Source:
Tetrahedron letters 2019 v.60 no.3 pp. 214-218
ISSN:
0040-4039
Subject:
moieties,   etc   ; chemical reactions; quinolines; regioselectivity;     Show all 4 Subjects
Abstract:
... A simple and efficient method has been developed for construction of sulfonylated quinolines via coupling of haloquinolines and sulfonyl chlorides in water. The present methodology provides an attractive approach to various sulfonylated quinolines in moderate to good yields with favorable functional group tolerance, which has the advantages of operation simplicity, readily available starting mater ...
DOI:
10.1016/j.tetlet.2018.12.016

5. Aromaticity can enhance the reactivity of P-donor/borole frustrated Lewis pairs

Author:
Cabrera-Trujillo, Jorge Juan; Fernández, Israel
Source:
Chemical communications 2019 v.55 no.5 pp. 675-678
ISSN:
1364-548X
Subject:
moieties,   etc   ; Lewis acids; chemical reactions;     Show all 3 Subjects
Abstract:
... Geminal frustrated Lewis pairs (FLPs) having a borole fragment as the Lewis acid partner constitute really promising candidates to achieve facile small molecule activation reactions. The predicted enhanced reactivity of these species, as compared to more traditional FLPs, finds its origin in the loss of the antiaromatic character of the borole moiety along the reaction coordinate. ...
DOI:
10.1039/c8cc09777a

6. Improved synthesis of the Kijanimicin oligodeoxytetrasaccharide

Author:
Thiem, Joachim; Sajus, Henry
Source:
Carbohydrate research 2019 v.471 pp. 19-27
ISSN:
0008-6215
Subject:
moieties,   etc   ; glycosides; methyl ethers; stereoselectivity;     Show all 4 Subjects
Abstract:
... By sequential synthesis the four 2,6-dideoxy saccharide moieties of the kijanimicin tetrasaccharide could be stereoselectively assembled. For formation of all required 2-deoxy α-glycoside linkages various S-(hexopyranosyl)-phosphorodithioates as donor structures could be convincingly employed. The terminal 2-deoxy β-glycoside linkage was stereoselectively formed following the dibromomethyl methyl ...
DOI:
10.1016/j.carres.2018.10.014

7. Identifying the stacking style, intrinsic bandgap and magnetism of pristine graphdyine

Author:
Lin, Lihua; Pan, Hongzhe; Chen, Yanhuan; Song, Xiaoying; Xu, Jun; Liu, Huibiao; Tang, Shaolong; Du, Youwei; Tang, Nujiang
Source:
Carbon 2019 v.143 pp. 8-13
ISSN:
0008-6223
Subject:
moieties,   etc   ; annealing; carbon; hydrogen; paramagnetism; semiconductors;     Show all 6 Subjects
Abstract:
... Pristine graphdiyne (pGDY) with high quality was prepared by annealing as-prepared GDY in hydrogen, and its stacking style, bandgap and magnetism were studied. The results show that pGDY is ABC-stacked, has a direct bandgap of ca. 0.64 eV, and shows spin-half paramagnetism at 2 K which may result from the residual hydroxyl groups on the chains of GDY sheet. The hybrid functional calculations show ...
DOI:
10.1016/j.carbon.2018.10.001

8. Ligand-controlled, transition-metal catalyzed site-selective modification of glycosides

Author:
Shang, Weidong; He, Bin; Niu, Dawen
Source:
Carbohydrate research 2019 v.474 pp. 16-33
ISSN:
0008-6215
Subject:
moieties,   etc   ; catalytic activity; derivatization; glycosides; ligands;     Show all 5 Subjects
Abstract:
... Carbohydrates play important roles in many physiological and pathological events. The preparation of the derivatives and conjugates of carbohydrates is often needed to help interrogate and exploit their biological properties. Owning to their structural complexity, one major challenge in the derivatization of carbohydrates is to control site-selectivity, that is, to selectively modify one hydroxyl ...
DOI:
10.1016/j.carres.2019.01.006

9. Critical Role of Achiral Guest Molecules in Planar Chirality Inversion of Alanine-Appended Pillar[5]arenes

Author:
Park, Jaehyeon; Choi, Yeonweon; Lee, Shim Sung; Jung, Jong Hwa
Source:
Organic letters 2019 v.21 no.4 pp. 1232-1236
ISSN:
1523-7052
Subject:
moieties,   etc   ; alanine; aromatic hydrocarbons; imidazoles; optical isomerism;     Show all 5 Subjects
Abstract:
... Planar chirality inversion of pillar[5]arenes bearing d- or l-alanine substituents on both rims was investigated upon addition of guest molecules having pyridinium or imidazole moieties and long alkyl chains. The d- and l-alanine-substituted pillar[5]arenes exhibited pS and pR planar chirality, respectively. However, this planar chirality was inverted upon inclusion of certain achiral molecules, c ...
DOI:
10.1021/acs.orglett.9b00277

10. Hydride Transfer Involved Redox-Neutral Cascade Cyclizations for Construction of Spirocyclic Bisoxindoles Featuring a [3,4]-Fused Oxindole Moiety

Author:
Li, Shuai-Shuai; Zhu, Shuai; Chen, Chunqi; Duan, Kang; Liu, Qing; Xiao, Jian
Source:
Organic letters 2019 v.21 no.4 pp. 1058-1062
ISSN:
1523-7052
Subject:
moieties,   etc   ; cyclization reactions; diastereoselectivity; hydrides; organic compounds;     Show all 5 Subjects
Abstract:
... The hydride transfer involved redox-neutral cascade cyclization has been developed to construct the spirocyclic bisoxindoles featuring a [3,4]-fused oxindole moiety from rationally designed C4-amine-substituted isatins, affording the diverse tricyclic [3,4]-fused oxindoles with three consecutive chiral centers in good yields and excellent diastereoselectivities (>20:1). ...
DOI:
10.1021/acs.orglett.8b04100

11. Field emission properties of edge-functionalized graphene

Author:
Gao, Yanlin; Okada, Susumu
Source:
Carbon 2019 v.142 pp. 190-195
ISSN:
0008-6223
Subject:
moieties,   etc   ; density functional theory; electric field; graphene;     Show all 4 Subjects
Abstract:
... A comprehensive study on electrostatic potential properties of edge-functionalized graphene under an external electric field was performed by using the density functional theory. The shapes and attached functional groups of the edges cause substantial variation of their electrostatic potential outside the edges. Our calculations reveal that graphene edges functionalized by H, OH, and COOH cause re ...
DOI:
10.1016/j.carbon.2018.10.019

12. Robust micropatterns on graphene oxide films based on the modification of fluorescence lifetime for multimode optical recording

Author:
Qiao, Zhixing; Qin, Chengbing; He, Wenjun; Gong, Yani; Li, Bin; Zhang, Guofeng; Chen, Ruiyun; Gao, Yan; Xiao, Liantuan; Jia, Suotang
Source:
Carbon 2019 v.142 pp. 224-229
ISSN:
0008-6223
Subject:
moieties,   etc   ; carbon; fluorescence; graphene oxide; information storage;     Show all 5 Subjects
Abstract:
... Here we report on the fine modification of fluorescence lifetime of graphene oxide (GO) film by introducing a localized writing process with a well-controlled reduction degree. The modification results from the elimination of long-lived sp3 functional groups and/or the conversion of that to short-lived sp2 confined clusters. By optimizing the parameters of writing process, four-lifetime distributi ...
DOI:
10.1016/j.carbon.2018.10.046

13. Studying the reduction of graphene oxide with magnetic measurements

Author:
Kim, Soo-Whan; Kim, Hyun-Kyung; Lee, Kyujoon; Roh, Kwang Chul; Han, Joong Tark; Kim, Kwang-Bum; Lee, Sunghun; Jung, Myung-Hwa
Source:
Carbon 2019 v.142 pp. 373-378
ISSN:
0008-6223
Subject:
moieties,   etc   ; graphene; graphene oxide; magnetism; spectroscopy;     Show all 5 Subjects
Abstract:
... The reduction of graphene oxide is one of the most facile methods to fabricate a large amount of graphene. The reduction rate is generally examined by various spectroscopic techniques, but each technique is applied for different purposes. Herein, we demonstrate the correlation between spectroscopic results and magnetic data, which plays an important role in determining the quality of reduced graph ...
DOI:
10.1016/j.carbon.2018.10.068

14. Tuning microwave absorption properties of multi-walled carbon nanotubes by surface functional groups

Author:
Hu, Chenglong; Liu, Haopeng; Zhang, Yanhui; Zhang, Mu; Yu, Jieyi; Liu, Xianguo; Zhang, Xuefeng
Source:
Journal of materials science 2019 v.54 no.3 pp. 2417-2426
ISSN:
0022-2461
Subject:
moieties,   etc   ; absorption; carbon nanotubes; electrical conductivity; engineering;     Show all 5 Subjects
Abstract:
... Multi-walled carbon nanotubes (MWCNTs) have been proven effective for microwave absorption due to the high dielectric loss capacity; however, the influence of surface functional groups on the absorption efficiency still remains unknown. Herein, we investigated the microwave absorption properties of pristine MWCNTs, hydroxyl-containing MWCNTs and carboxyl-containing MWCNTs, evidencing the absorptio ...
DOI:
10.1007/s10853-018-2895-y

15. Nickel-Catalyzed Carbonylation of Difluoroalkyl Bromides with Arylboronic Acids

Author:
Zhao, Hai-Yang; Gao, Xing; Zhang, Shu; Zhang, Xingang
Source:
Organic letters 2019 v.21 no.4 pp. 1031-1036
ISSN:
1523-7052
Subject:
moieties,   etc   ; acids; chemical reactions; nickel; organobromine compounds;     Show all 5 Subjects
Abstract:
... A nickel-catalyzed carbonylative difluoroalkylation reaction with arylboronic acids under 1 atm of CO has been developed. The reaction proceeds under mild reaction conditions with high efficiency and high functional group tolerance. Preliminary mechanistic studies reveal that the arylacyl nickel complex is the key intermediate to circumvent the formation of labile fluoroacyl nickel, and bimetallic ...
DOI:
10.1021/acs.orglett.8b04070

16. Total Synthesis and Structural Elucidation of (−)-Cephalezomine G

Author:
Jeon, Hongjun; Cho, Hyunkyung; Kim, Sanghee
Source:
Organic letters 2019 v.21 no.4 pp. 1121-1124
ISSN:
1523-7052
Subject:
moieties,   etc   ; optical isomerism; organic compounds; proline; stereoselectivity;     Show all 5 Subjects
Abstract:
... The first asymmetric synthesis and configurational elucidation of (−)-cephalezomine G was achieved. The highly functionalized Cα-substituted proline derivative was prepared from d-proline as the only chiral source via a C → N → C chirality transfer method consisting of stereoselective N-allylation and [2,3]-Stevens rearrangement. The azaspiranic tetracyclic backbone was constructed using ring-clos ...
DOI:
10.1021/acs.orglett.9b00036

17. Photoredox- or Metal-Catalyzed in Situ SO₂-Capture Reactions: Synthesis of β-Ketosulfones and Allylsulfones

Author:
Zheng, Min; Li, Guigen; Lu, Hongjian
Source:
Organic letters 2019 v.21 no.4 pp. 1216-1220
ISSN:
1523-7052
Subject:
moieties,   etc   ; additives; chemical reactions; oximes; sulfur dioxide;     Show all 5 Subjects
Abstract:
... The first report of the in situ capture of the SO₂ fragment of the trifluoromethylsulfonyl radical is described here. With cyclobutanone oximes as representative alkyl radical precursors, vinyl triflates and allyl trifluoromethylsulfones were employed as radical acceptors and SO₂ sources to provide various β-ketosulfones and allylsulfones, known to be significant building blocks. Without the use o ...
DOI:
10.1021/acs.orglett.9b00201

18. Cobalt(III)-Catalyzed [4 + 2] Annulation of N-Chlorobenzamides with Maleimides

Author:
Muniraj, Nachimuthu; Prabhu, Kandikere Ramaiah
Source:
Organic letters 2019 v.21 no.4 pp. 1068-1072
ISSN:
1523-7052
Subject:
moieties,   etc   ; ambient temperature; amides; chemical reactions; cobalt;     Show all 5 Subjects
Abstract:
... A Co(III)-catalyzed novel [4 + 2] annulation of N-chlorobenzamides with maleimides has been reported. Mostly, maleimides are known to furnish the Michael-type or 1,1-type cyclized products while treating with amides. In this reaction, maleimides furnished [4 + 2] annulated products in good yields at room temperature while being treated with the internal oxidizing N-chlorobenzamide as a directing g ...
DOI:
10.1021/acs.orglett.8b04117

19. Amide-Directed Cobalt(III)-Catalyzed C–H Amidation of Ferrocenes

Author:
Huang, Dan-Ying; Yao, Qi-Jun; Zhang, Shuo; Xu, Xue-Tao; Zhang, Kun; Shi, Bing-Feng
Source:
Organic letters 2019 v.21 no.4 pp. 951-954
ISSN:
1523-7052
Subject:
moieties,   etc   ; chemical reactions; cobalt; nitrogen; organic compounds;     Show all 5 Subjects
Abstract:
... The amide-directed cobalt(III)-catalyzed C–H amidation of ferrocene carboxamides using 1,4,2-dioxazol-5-ones as robust and efficient amidating reagents has been developed. This reaction proceeds efficiently under mild reaction conditions with good functional group tolerance, providing expedient access to a broad range of ferrocenes containing a nitrogen group on the Cp ring. ...
DOI:
10.1021/acs.orglett.8b03938

20. Thermally Activated Delayed Fluorescent Materials Combining Intra- and Intermolecular Charge Transfers

Author:
Zhang, Dong-dong; Suzuki, Katsuaki; Song, Xiao-zeng; Wada, Yoshimasa; Kubo, Shosei; Duan, Lian; Kaji, Hironori
Source:
ACS applied materials & interfaces 2019 v.11 no.7 pp. 7192-7198
ISSN:
1944-8252
Subject:
moieties,   etc   ; fluorescence; materials science; mixing; phosphorescence;     Show all 5 Subjects
Abstract:
... A novel thermally activated delayed fluorescent (TADF) compound, 9-(3-((4,6-diphenyl-1,3,5-triazin-2-yl)oxy)phenyl)-3,6-diphenyl-9H-carbazole (PhCz-o-Trz), with a donor−σ–acceptor (D−σ–A) motif is developed. A flexible small space σ-junction is adopted to partly suppress the intramolecular charge transfer (intra-CT) while inversely enhancing the intermolecular charge transfer (inter-CT) between D/ ...
DOI:
10.1021/acsami.8b19428