Synthesis of Chiral Esters via Asymmetric Wolff Rearrangement Reaction
作者:Jing Meng、Wei-Wei Ding、Zhi-Yong Han
DOI:10.1021/acs.orglett.9b03227
日期:2019.12.20
The first asymmetric Wolff rearrangement reaction that directly converts α-diazoketones into broadly useful chiral α,α-disubstituted carboxylic esters with high enantioselectivities (up to 97.5:2.5 er) is reported. The cascade reaction proceeds through the seamless combination of visible-light-induced formation of the ketene intermediate and asymmetric ketene esterification using a readily available
An efficient asymmetric intramolecular trapping of ammonium ylides of α-diazoketones with enones to synthesize indoline derivatives was realized. A Rh(II)/chiralN,N′-dioxide−Sc(III) complex bimetallic relay catalytic system was established. A series of optically active 2,2,3-trisubstituted indolines were obtained in high yields (up to 99%), good enantioselectivities (up to 99% ee), and excellent
cycloadditions, and the utilization of their recently realized reactivities to construct new cyclic architectures is of great significance in modern synthetic chemistry. Herein, a palladium‐catalyzed, visible‐light‐driven, asymmetric [5+2] cycloaddition of VCPs with α‐diazoketones is accomplished by switching the reactivity of the Pd‐containing dipolar intermediate from an all‐carbon 1,3‐dipole to an oxo‐1
An efficient asymmetricsynthesis of isochromanone derivatives was realized through Z-selective-1,3-OH insertion/aldol cyclization reaction involving acyclic carboxylic oxonium ylides. The combination of achiral dirhodium salts and chiral N,N′-dioxide–metal complexes, along with the use of α-diazoketones instead of α-diazoesters, enables the cascade reaction efficiently. A variety of benzo-fused δ-lactones
enynamides and α-diazoketones to produce chiral bicyclic lactams bearing chiral all-carbon quaternary stereocenters is realized with up to 95% yield, 98% ee, and >19:1 dr. The combination of visible light photoactivation and the relay of gold and N-oxide catalysis in a cascade process enabled the facile generation and controlled assembly of two reactive intermediates, ketene and aza-o-quinone methide