A stereoselective annulative coupling of a vinylboronic ester ate-complex with arynes producing cyclic borinic esters has been developed. An annulation reaction that proceeded through the formation of two C–C bonds and a C–B bond was realized by exploiting a 1,2-metallate rearrangement of boronate triggered by the addition of a vinyl group to the strained triple bond of an aryne. The generated aryl
The first 1,3-boronate rearrangement to ketones is reported. The reaction is driven by visible light irradiation, leading to various β-keto tertiary alcohols under metal-free conditions. The excited state overcomes the energy barrier for the rearrangement, and mechanistic studies have excluded a free-radical reaction pathway.