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.
AbstractAn eco-friendly and efficient synthesis of nitrones is presented by condensation of an equimolar amount of aldehydes and N-substituted hydroxylamine hydrochlorides in glycerol as a recyclable solvent-catalyst. This novel protocol provides rapid and mild access to a series of nitrone derivatives in good to excellent yields in the absence of catalyst and base. Graphic abstractSYNOPSIS In this
An efficient C2-homologation of aromatic aldehydes via 5-hydroxyisoxazolidines
作者:L Di Nunno、A Scilimati
DOI:10.1016/s0040-4020(01)86449-8
日期:1991.1
The reaction of lithiumenolate of acetaldehyde (generated by the known cycloreversion of THF in the presence of n-BuLi) with a number of aryl N-phenylnitrones affords 2-phenyl-3-aryl-5-hydroxyisoxazolidines (trans + cis) in high yields. A low conversion or no reaction at all were instead observed with some N-alkylnitrones (methyl and t-butyl, respectively). Base (or acid) induced decomposition of
<i>α</i>-(Trifluoromethyl)amine Derivatives via Nucleophilic Trifluoromethylation of Nitrones
作者:Derek W. Nelson、James Owens、Diana Hiraldo
DOI:10.1021/jo000685l
日期:2001.4.1
(Trifluoromethyl)trimethylsilane (TMSCF(3)) reacts with nitrones to afford alpha-(trifluoromethyl)hydroxylamines protected as O-trimethylsilyl ethers. Potassium t-butoxide initiates the nucleophilic trifluoromethylation. The reaction works best with alpha,N-diaryl nitrones, and the conditions are compatible with a range of substituents on the aryl groups. Acidic deprotection of the nitrone/TMSCF(3)