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A Novel Enantioselective Catalytic Tandem Oxa-Michael–Henry Reaction: One-Pot Organocatalytic Asymmetric Synthesis of 3-Nitro-2H-chromenes

✍ Scribed by Dan-Qian Xu; Yi-Feng Wang; Shu-Ping Luo; Shuai Zhang; Ai-Guo Zhong; Hui Chen; Zhen-Yuan Xu

Publisher: John Wiley and Sons
Year: 2008
Tongue: English
Weight: 224 KB
Volume: 350
Category: Article
ISSN: 1615-4150
DOI: 10.1002/adsc.200800535

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✦ Synopsis

Abstract

An enantioselective oxa‐Michael–Henry reaction of substituted salicylaldehydes with nitroolefins that proceeds though an aromatic iminium activation (AIA) has been developed by using a chiral secondary amine organocatalyst and salicylic acid as a co‐catalyst. The corresponding 3‐nitro‐2__H__‐chromenes were obtained in moderate‐to‐good yields with up to 91% ee under mild conditions. Based on the experimental results and ESI‐mass spectrometric detection of the intermediates, a plausible transition state has been proposed to explain the origin of the activation and the asymmetric induction.

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