Unravelling the underlying mechanism of the reduction of aldehydes/ketones with metal borohydride in an aprotic solvent

The mechanism of aldehyde/ketones with M(BH 4 ) n in aprotic solvents has been elucidated as a six-membered ring, in which hydride transfer to the C atom from the B atom, formation of L·BH 3 adduct, and disproportionation of BH 3 (OR) − may be involved.