Reduction of Aldehydes and Ketones to Alcohols
Reduction of Aldehydes and Ketones to Alcohols: Mechanism of Sodium Borohydride Reduction
The reaction of carbonyl compounds with metal hydrides involves the nucleophilic transfer of a hydride anion to the carbonyl carbon atom. Activation is provided by the metal cation which is coordinated with the carbonyl oxygen atom.
The resulting boron alkoxide is able to transfer three more hydride anions.