Construction of Spiro-Fused 2-Oxindole/α-Methylene- γ-Butyrolactone Systems with Extremely High Enantioselectivity via Indium-Catalyzed Amide Allylation of <i>N</i>-Methyl Isatin

Abstract

A remarkably effective method allowing an extremely high enantioselective synthesis of the spiro-fused 2-oxindole/α-methylene-γ-butyrolactones is described. The key strategy lies in the use of indium-catalyzed asymmetric amide allylation of N-methyl isatin with functionalized allylstannanes, which can lead to the antineoplastic spirocyclic lactones in almost enantiopure forms.