Chiral Lewis Acid-Catalyzed Norrish Type II Cyclization to Synthesizeα-Oxazolidinones via Enantioselective Protonation  

作　　者：Tangyu Zhan Liangkun Yang Qiyou Chen Rui Weng Xiaohua Liu Xiaoming Feng 

机构地区：[1]Key Laboratory of Green Chemistry and Technology,Ministry of Education,College of Chemistry,Sichuan University,Chengdu 610064

出　　处：《CCS Chemistry》2023年第9期2101-2110,共10页中国化学会会刊（英文）

基　　金：the financial support of the National Natural Science Foundation(grant no.22188101);the Science and Technology Department of Sichuan Province(grant no.2021YJ0561);Sichuan University(grant no.2020SCUNL204)for financial support.

摘　　要：The Norrish type II reaction is an interesting photochemical process through Csp3-H functionalization of N,N-disubstituted oxo-amine or oxo-amide provides access to diverse synthetic building blocks by different pathways.Due to the finite lifetime of the excited state and rapid changes in the intermediates,there are significant challenges in controlling the stereochemical outcomes of this reaction over the strong racemic background reaction.The oxazolidin-4-one skeleton is a useful structural motif found in bioactive molecules,and it is the one that is produced by a not well-studied route among the three routes in Norrish type II cyclization.Herein we report the asymmetric version of this process,and a variety of oxazolidin-4-ones is achieved from arylα-oxoamides via triplet excimers with three H-transfer steps interspersed by a cyclization step under mild,visible light.In the presence of chiral N,N-dioxide/metal complex catalysts,diastereo-and enantiocontrol in this photochemical reaction happens with enantioselective protonation of enol intermediates as the crucial stereo-determining step,getting the better of the thermodynamical control pathway.Trans-oxazolidine-4-ones can be obtained in high enantioselectivity,which can be transferred into optically active cis-oxazolidine-4-ones after the treatment with a base.

关 键 词：asymmetric catalysis Norrish type II reaction enantioselective protonation PHOTOCATALYSIS α-oxazolidinones 

分 类 号：O657.34[理学—分析化学]