Stereoselective Addition of Organoaluminium or Organomanganese Reagents to α-Formyl Amides or α-Methyl-Substituted β-Keto Amides

Treatment of α-formyl amides with RAlCl2 or PhAlCl2 provided threo-α-alkyl-substituted β-hydroxy amides under high stereocontrol. The method was successfully applied to the selective addition of alkyl group to α-methyl-substituted β-keto amides or esters. Treatment of α-methyl-β-keto amides or α-methyl-β-keto esters with trialkylaluminium or alkylmanganese halide afforded the corresponding erythro (or threo) α-methyl-substituted β-hydroxy amides or α-methyl-substituted β-hydroxy esters with high stereoselectivity.