Cyanide‐Catalyzed Additions of Acyl Phosphonates to Aldehydes: A New Acyl Donor for Benzoin‐Type Reactions

Abstract 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.