Atom swap in triple bonds via nitrogen-deletion coupling with gem-diborylalkanes

Abstract

Alkynes have played pivotal roles in numerous synthetic transformations and materials science. Here, by developing nitrogen-deletion coupling, we describe a modular synthesis of alkynes from widely accessible nitriles by swapping the N atom to a C atom in cyano groups, where lithiated gem-diborylalkanes and tert-butyl nitrite are applied sequentially. NMR analysis and crystal structure show the nature of an intermediary α-boryl lithium enamine. A diverse range of nitriles are converted into various internal and terminal alkynes within a short reaction time, including alkynes bearing bulky secondary and tertiary alkyl substituents on both sides.