Donor-Acceptor Assisted Alkyne Hydration: A Luminescent Boron-Stabilized Enol

An alkyne molecule 2-(2'-BMes(2)-phenylethynyl)pyridine (1) that contains a Lewis acidic BMes(2) group and a Lewis basic pyridyl group has been found to undergo facile hydration under ambient conditions in the presence of Cul, forming a highly emissive and stable enol ester (2). The lack of any hydration reactivity by a control compound 2-(2'-BMes(2)-phenylethynyl)benzene (3) under the same conditions supports that the cooperativity between the Lewis donor and acceptor groups plays a key role in the formation of 2.