5‐di‐tert‐butyl‐4‐methoxyphenyl)phosphino]‐4,4′‐bi‐1,3‐benzodioxole–PdCl2 [(R)‐SEGPHOS–PdCl2], 5‐endo‐hydroaminocyclization of achiral ortho‐alkynylanilines proceeds in an enantioselective manner to give optically active, axially chiralindoles (see scheme).
Palladium-Catalyzed Asymmetric 1,4-Addition of Diarylphosphines to α,β-Unsaturated Sulfonamides
作者:Fanhua Xiao、Wei-Liang Duan、Guo-Fa Dai、Yu-Chuan Song
DOI:10.1055/s-0036-1591593
日期:2018.9
Abstract A pincer palladium-catalyzedasymmetric 1,4-addition of diarylphosphines to α,β-unsaturated sulfonamides was realized for the synthesis of chiral sulfonamide phosphines with up to 98% ee under mild conditions. A pincer palladium-catalyzedasymmetric 1,4-addition of diarylphosphines to α,β-unsaturated sulfonamides was realized for the synthesis of chiral sulfonamide phosphines with up to 98%
In the presence of (R)-SEGPHOS-PdCl2 catalyst, 5-endo-hydroaminocyclization of various 2-(tert-butyl)-N-(2-ethynylphenyl)anilines proceeds enantioselectively to afford optically active N-C axially chiral N-(2-tert-butylphenyl)indole derivatives in good yields. The enantioselectivity depends strongly on the bulkiness of ortho-substituents and the electron density on the arylethynyl group, and it is explained by the dynamic axial chirality generated by the twisting of the aryl substituent. (C) 2015 Elsevier Ltd. All rights reserved.
Molecular-Iodine-Catalyzed Cyclization of 2-Alkynylanilines via Iodocyclization–Protodeiodination Sequence
Molecular iodine catalyzes a cyclization of N-ary1-2-alkynylanilines, which proceeds through the iodocyclization of 2-alkynylanilines followed by the protodeiodination of the iodocyclized intermediates at room temperature. Furthermore, the molecular iodine catalysis can be applied to the cascade cyclization of 2-(enynyl)aniline and to the tandem cyclization addition reaction of 2-alkynylanilines with alpha,beta-enones.