Cyanide-catalyzed additions of acyl phosphonates to aldehydes: A new acyl donor for benzoin-type reactions

Acyl phosphonates have been utilized as new acyl donors for cyanide-catalyzed benzoin-type reactions. Cyanation of acyl phosphonates, followed by a [1,2]-phosphoryl migration generates the active acyl anion intermediate. The presumed (cyano)phosphate anion reacts with a variety of aryl aldehydes to yield phosphate ester-protected, unsymmetrical benzoins in good to excellent yields. The unsymmetrical benzoin product can be obtained after deprotection of the phosphate ester with an aqueous amine solution.