Catalytic Asymmetric Alkylation of 3‐Aryl‐Substituted Oxindoles to give 3,3‐Disubstituted Oxindoles under Phase‐Transfer Conditions

An efficient enantioselective method for the construction of all‐carbon quaternary stereocenters from 3‐aryl‐substituted oxindoles via asymmetric phase‐transfer alkylation has been developed. The products are obtained in high yields and optical purity of up to 93 % ee by using (S,S)‐3,4,5‐trifluorophenyl‐NAS bromide as a chiral phase‐transfer catalyst. The 3,3‐disubstituted oxindole products are valuable intermediates for the synthesis of bioactive indole‐containing natural products.