Theoretical insights on boron reducing agent for the reduction of carbonyl compounds

In this perspective, we present computational progress in the reduction of carbonyl compounds using boron reducing agents, such as L·BH3, HBcat, HBpin, and 9-BBN. For the catalytic reduction reactions, establishing a catalytic mechanism will provide an important theoretical basis for the improvement of a more efficient combination of reducing agents and catalysts. Current computational studies reveal that the mechanisms of reactions are different due to the various combinations of electrophilic boron reducing agents and catalysts (transition-metal catalyst, main group metal catalysts, and metal-free frustrated Lewis pair). We discuss the role of boron reducing agents on the efficiency of reactions and believe that possible Lewis acid–base interaction between Bδ+, Mδ+ and Oδ−, Hδ− existing in boron reducing agent, unsaturated substances, and catalyst should be considered fully. A tentative outlook on future opportunities of this research field is proposed.