α-Hydroxyboronate Esters: Formation and Synthetic Applications

The synthesis of -oxyboronate esters by the copper-catalyzed diboration of carbonyls provides a facile method to access these versatile intermediates. The evolution of diboration conditions and approaches to allow the isolation of products derived from -hydroxyboronate esters is discussed. Both experimental and computational evidence for the mechanism of the copper-catalyzed diboration reaction distinguishes the potential pathways of the key migratory insertion of the carbonyl into the copper-boron bond. -Hydroxyboronate esters and their derivatives have been used in a number of synthetic transformations, including homologation, coupling, and elimination reactions.