Formal [3 + 2] cycloaddition of α-unsubstituted isocyanoacetates and methyleneindolinones: enantioselective synthesis of spirooxindoles

Abstract

The first enantioselective formal [3 + 2] cycloaddition of α-unsubstituted isocyanoacetates with protecting-group-free methyleneindolinones was developed. A variety of optically enriched 3,3′-pyrrolidinyl spirooxindoles were obtained in excellent yields, and diastereo- and enantioselectivities (up to 99% yield, >20 : 1 dr, 99% ee) with low catalyst loading under mild reaction conditions.