Diastereoselective Synthesis of Functionalized Spirocyclopropyl Oxindoles via P(NMe₂)₃-Mediated Reductive Cyclopropanation

Abstract

A P(NMe2)3-mediated reductive cyclopropanation reaction of α-keto esters or amides with isatin-derived alkenes has been developed, providing efficient and diastereoselective synthesis of highly functionalized spirocyclopropyl oxindoles bearing two all-carbon quaternary centers. This reaction also represents a complementary and nonmetal-involving protocol for the challenging cyclopropanation of electron-deficient alkenes.