N–H / P–H bond activation of ammonia, amines and phosphines at a transient borylene

Abstract

The metal-free activation of amines and phosphines is of great significance due to its broad relevance in both organic synthesis and industrial chemistry. Herein, we report the cooperative 1,2-addition of N–H bonds from ammonia as well as various primary and secondary amines, and the 1,1-addition of P–H bonds from primary phosphines, across the C=B double bond of a transient cyclic (alkyl)(amino)carbene (CAAC)-stabilized arylborylene. This transient borylene species displays remarkable ambiphilicity, enabling selective, metal-free activation of amines and phosphines. Mechanistic studies reveal distinct activation pathways dictated by the electronic and steric properties of the substrates, highlighting the unique reactivity of CAAC-stabilized borylenes.