Enantioselective thiourea-catalyzed cationic polycyclizations

Abstract

A new thiourea catalyst is reported for the enantioselective cationic polycyclization of hydroxylactams. Both the yield and enantioselectivity of this transformation were found to vary strongly with the identity of a single aromatic residue on a common catalyst framework, with more expansive and polarizable arenes proving optimal. Evidence is presented for a mechanism in which stabilizing cation?π interactions are a principal determinant of enantioselectivity. © 2010 American Chemical Society.