Iridium-catalyzed regioselective B(3,6)-dialkenylation or B(4)-alkenylation of o-carboranes via B–H activation and 1,2-carbon migration of alkynes

Abstract

An efficient Ir-catalyzed cage boron vertex alkenylation of 1-(2’-picolyl)-o-carboranes with diarylacetylenes has been developed, leading to a wide variety of B–H geminal addition products via 1,2-carbon migration of alkynes. The...

Palladium-Catalyzed Regioselective B(3,5)-Dialkenylation and B(4)-Alkenylation of o-Carboranes

“…12−14 On the other hand, B (3,6)−H or B(4)−H geminal addition via 1,2-carbon migration of alkynes was developed under the assistance of the picolyl directing group at cage C(1). 15 The degree of substitution and regioselectivity were determined by the cage C(2)-substituents due to steric reasons (Scheme 1d). Replacement of the Ir by Pd catalyst in the aforementioned reaction offered unprecedentedly a B(3,5)−H regioselectivity, 9 which was very different from that of Ir catalysis.…”

“…The configurations of the resultant olefins were controlled by the nature of the alkyne substituents (Scheme a and b) . A carboxy or acetylamino directing group assisted Ir­(III) catalyzed B(4)-alkenylation was reported to perform in a cis -addition manner (Scheme c). − On the other hand, B­(3,6)–H or B(4)–H geminal addition via 1,2-carbon migration of alkynes was developed under the assistance of the picolyl directing group at cage C(1) . The degree of substitution and regioselectivity were determined by the cage C(2)-substituents due to steric reasons (Scheme d).…”