Mechanism of Bronsted-Base-Mediated Borylation of Propynols: A DFT Study

DFT calculations are used to reveal the mechanism of Bronsted-base-mediated borylation of propynols. The reaction is predicted to go through a key intermediate of alkenylboronate. Therefore, the possible pathways involve two key steps, borylation and reductive dehydroxylation. The favored pathway for the generation of the alkenylboronate intermediate involves alkoxy exchange, methoxylation, electrophilic substitution, and protonation. Then, the final product is yielded by a second alkoxy exchange, intramolecular nucleophilic attack, beta-methoxy elimination, and protonation.