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.
Rhodium(III)‐Catalyzed Asymmetric Access to Spirocycles through C−H Activation and Axial‐to‐Central Chirality Transfer
作者:Lingheng Kong、Xi Han、Song Liu、Yun Zou、Yu Lan、Xingwei Li
DOI:10.1002/anie.202000174
日期:2020.4.27
Axial-to-central chirality transfer is an important strategy to construct chiral centers, where the axiallychiral reagents are mostly limited to atropomerically stable ones. Reported herein is a RhIII -catalyzed enantioselective spiroannulative synthesis of nitrones. The coupling proceeds via C-Harylation to give an atropomerically metastable biaryl, followed by intramolecular dearomative trapping
Catalyst Choice for Highly Enantioselective [3 + 3]-Cycloaddition of Enoldiazocarbonyl Compounds
作者:Kostiantyn O. Marichev、Frady G. Adly、Alejandra M. Carranco、Estevan C. Garcia、Hadi Arman、Michael P. Doyle
DOI:10.1021/acscatal.8b03391
日期:2018.11.2
Chiral copper(I) catalysts are preferred over chiral dirhodium(II) catalysts for [3 + 3]-cycloaddition reactions of enoldiazocarbonyl compounds with nitrones and acyliminopyridinium ylides, forming chiral oxazines and pyrazines in very high yield and enantioselectivity. Yields and stereoselectivitiesfrom reactions of enoldiazoketones are virtually the same as those from the corresponding esters and
A donor–acceptor cyclopropene as a dipole source for a silver(i) catalyzed asymmetric catalytic [3+3]-cycloaddition with nitrones
作者:Xinfang Xu、Peter J. Zavalij、Michael P. Doyle
DOI:10.1039/c3cc46415f
日期:——
Silver(I)-catalyzed asymmetric formal [3+3]-cycloaddition of nitrones with a donor-acceptor cyclopropene, formed in situ from dirhodium acetate-catalyzed dinitrogen extrusion/intramolecular cyclization of enoldiazoacetates, effectively generates 3,6-dihydro-1,2-oxazine derivatives in high yield and with exceptional stereocontrol.