An unprecedented strategy to access highly enantioenriched dihydropyrazoles is described. It involves formal [4+1] cycloadditions of in situ-derived azoalkenes and sulfurylides catalyzed by a chiral copper/Tol-BINAP complex. A variety of synthetically and biologically important dihydropyrazoles have been obtained with high enantioselectivities (up to 97:3 er) in good yields (83-97%).
Visible-Light-Driven Radical Multicomponent Reaction of 2-Vinylanilines, Sulfonyl Chlorides, and Sulfur Ylides for Synthesis of Indolines
作者:Mukund M. D. Pramanik、Fan Yuan、Dong-Mei Yan、Wen-Jing Xiao、Jia-Rong Chen
DOI:10.1021/acs.orglett.0c00602
日期:2020.4.3
A visible-light-driven photoredox-catalyzed multicomponent reaction of 2-vinylanilines, sulfonyl chlorides, and sulfur ylides is described. This protocol features redox-neutral mild conditions, a broad substrate scope, and good functional group tolerance, providing access to various sulfonated 2,3-disubstituted indolines. The product can be transformed to a diverse range of functionalized indoles by
Formal Diels–Alder Reactions of Chalcones and Formylcyclopropanes Catalyzed by Chiral N-Heterocyclic Carbenes
作者:Hui Lv、Junming Mo、Xinqiang Fang、Yonggui Robin Chi
DOI:10.1021/ol202250s
日期:2011.10.7
Highly enantioselective (formal) hetero-Diels–Alder reactions between chalcones and formylcyclopropanes are disclosed. The challenging N-heterocycliccarbene (NHC)-bounded enolate intermediates from formylcyclopropanes were captured for new C–C bond forming reactions. The reaction products were obtained with high diastereo- and enantioselectivities and could be easily transformed to optically pure
benzoxazinanones (4) with sulfur ylides (2) is reported. While the reactions of 4-vinyl/4-CF3 benzoxazinanones (1a/1c) with 2 furnished the 3-vinyl/3-CF3 indolines (3a/3c), via an attack on the C1 carbon of the π-allyl/benzyl zwitterionic intermediates, 4 was converted into 4-trifluoromethyl-dihydroquinolines (5) in good yields via an attack on the C3 carbon of the π-allyl intermediate. The corresponding
A visible-light-driven and room temperature photo-Wolff-Kischner reaction of sulfur ylides and N-tosylhydrazones has been developed for the first time to provide modular access to alkene synthesis. The high functional group tolerance and broad substrate scope were demonstrated by more than 60 examples. Both E- and Z-olefinic stereochemistry in the products could be controlled with excellent stereoselectivity