Addition of 3-Substituted Oxindoles to Vinyl Sulfone Catalyzed with Pentanidiums
Dr. Lili Zong, Shubo Du, Kek Foo Chin, Dr. Chao Wang and Prof. Dr. Choon‐Hong Tan
Angewandte Chemie International Edition, 2015, 54, 9390-9393
Abstract: A pentanidium‐catalyzed highly enantioselective conjugate addition of 3‐alkyloxindoles to phenyl vinyl sulfone has been demonstrated. This approach allows the construction of 3,3‐dialkyl‐substituted oxindole frameworks with high yield and excellent enantioselectivity (up to 99 %) under simple phase‐transfer conditions. A variety of oxindoles bearing all‐carbon quaternary stereogenic centers were obtained in the presence of 0.25 mol % pentanidium. Meanwhile, practicality was illustrated by a gram‐scale asymmetric synthesis of two 3,3‐dialkyl‐substituted oxindoles. The resulting adduct can be smoothly transformed to the natural product analogue in a short synthetic route.
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