Stereoselective preparation of cyclobutanes with four different substituents: total synthesis and structural revision of pipercyclobutanamide A and piperchabamide G

Abstract

A general strategy was developed for the diastereo- and enantioselective synthesis of cyclobutanes with four different substituents. It consists of three transition metal-catalyzed reactions — a Rh^II-catalyzed cyclopropanation, a Ag^I-catalyzed regioselective and stereospecific ring expansion, and a Rh^I-catalyzed addition reaction. Structures of pipercyclobutanamide A and piperchabamide G were synthesized and revised.