Oxygenation of aldimines and deoxygenation of nitrones on irradiated TiO2
摘要:
While aldimines have been selectively oxidized to nitrones in TiO2 suspended acetonitrile solution in the presence of O-2 upon irradiation, nitrones are reduced to their deoxygenated derivatives with retention of C=N by TiO2 photocatalysis under a nitrogen atmosphere. (C) 1998 Elsevier Science Ltd. All rights reserved.
Rhodium-Catalyzed Cyclization of Diynes with Nitrones: A Formal [2+2+5] Approach to Bridged Eight-Membered Heterocycles
作者:Chunxiang Wang、Dongping Wang、Hao Yan、Haolong Wang、Bin Pan、Xiaoyi Xin、Xincheng Li、Fan Wu、Boshun Wan
DOI:10.1002/anie.201407394
日期:2014.10.27
N‐aryl‐substituted nitrones were employed as five‐atom couplingpartners in the rhodium‐catalyzed cyclization with diynes. In this reaction, the nitrone moiety served as a directing group for the catalytic CHactivation of the N‐aryl ring. This formal [2+2+5] approach allows rapid access to bridged eight‐membered heterocycles with broad substrate scope. The results of this study may provide new insight
Iron-Catalyzed Cyclization of Nitrones with Geminal-Substituted Vinyl Acetates: A Direct [4 + 2] Assembly Strategy Leading to 2,4-Disubstituted Quinolines
作者:Mingbing Zhong、Song Sun、Jiang Cheng、Ying Shao
DOI:10.1021/acs.joc.6b01910
日期:2016.11.18
An iron-catalyzed intermolecular [4 + 2] cyclization of arylnitrones with geminal-substituted vinyl acetates was developed for the synthesis of 2,4-disubstituted quinolines in moderate to good yields with good functional group compatibilities. Preliminary mechanistic studies suggest a plausible iron-catalyzed C–H activation process under external-oxidant-free conditions.
Rh(III)-Catalyzed C–H Cyclization of Arylnitrones with Diazo Compounds: Access to 3-Carboxylate Substituted<i>N</i>-Hydroxyindoles
作者:Yazhou Li、Jian Li、Xiaowei Wu、Yu Zhou、Hong Liu
DOI:10.1021/acs.joc.7b01393
日期:2017.9.1
Recently, N-hydroxyindole derivatives have received much interest because of their unique structural motif and various biological activities. In this study, we report the first example of a Rh(III)-catalyzed reaction of arylnitrones with α-diazoketoesters or α-diazodiketones to produce N-hydroxyindole derivatives. Intriguingly, we could build the N-hydroxyindole scaffold by blocking the cleavage of
Rhodium-Catalyzed CH Annulation of Nitrones with Alkynes: A Regiospecific Route to Unsymmetrical 2,3-Diaryl-Substituted Indoles
作者:Hao Yan、Haolong Wang、Xincheng Li、Xiaoyi Xin、Chunxiang Wang、Boshun Wan
DOI:10.1002/anie.201503997
日期:2015.9.1
of anilines or related compounds with internal alkynes provides straightforward access to 2,3‐disubstituted indole products. However, this transformation proceeds with poor regioselectivity in the synthesis of unsymmetrically 2,3‐diaryl substituted indoles. Herein, we report the rhodium(III)‐catalyzed CH annulation of nitrones with symmetrical diaryl alkynes as an alternative method to prepare 2,
Catalytic Diastereo- and Enantioselective Synthesis of 2-Imidazolinones
作者:Pablo Martínez-Pardo、Gonzalo Blay、Alba Escrivá-Palomo、Amparo Sanz-Marco、Carlos Vila、José R. Pedro
DOI:10.1021/acs.orglett.9b01244
日期:2019.6.7
Chiral cyclic ureas (2-imidazolinones) were prepared by the reaction of nitrones and isocyanoacetate esters using a multicatalytic system that combines a bifunctional Brønsted base–squaramide organocatalyst and Ag+ as a Lewis acid. The reaction could be achieved with a range of nitrones derived from aryl- and cycloalkylaldehydes with moderate diastereo- and good enantioselectivity. A plausible mechanism