Generation of Arynes via Ate Complexes of Arylboronic Esters with an <i>ortho</i>-Leaving Group

Abstract

An efficient method of generating aryne has been achieved by treating <i>ortho</i>-(trifluoromethanesulfonyloxy)arylboronic acid pinacol ester with <i>tert</i>- or <i>sec</i>-butyllithium. Monitoring the reaction by ¹¹B NMR has indicated that a boron-ate complex formed in situ is the eventual precursor that converts into aryne near room temperature. The prior formation of the ate complex at a low temperature has enabled us to use various arynophiles, including those bearing base-sensitive groups. The ready availability of the aryne precursors and mutual orthogonality in aryne generation with widely used <i>ortho</i>-silylaryl triflate have enhanced the utility of the method