Transition metal catalyzed selective B(3)–H or B(4)–H amination of o-carboranes via dehydrogenative BH/NH cross-coupling

Abstract

A unique approach to vertex-selective catalytic B–H amination at either the B(3)- or B(4)-position in o-carboranes has been developed. Using different transition metal catalysts, dehydrogenative BH/NH cross-coupling of o-carboranes and free amines has been achieved, leading to a wide variety of cage B(3)- or B(4)-aminated o-carboranes in moderate to high yields with excellent regioselectivity, where carboranyl carboxylic acids and amines can serve as competent coupling partners without any pre-functionalization. The isolation and structural identification of a key intermediate provide an insight into the reaction mechanism in the catalytic B(4)–H amination.