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

A P(NMe2)(3)-mediated reductive cyclopropanation reaction of alpha-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.