Phosphorodiamidic Acid as a Novel Structural Motif of Br?nsted Acid Catalysts for Direct Mannich Reaction of N-Acyl Imines with 1,3-Dicarbonyl Compounds

Phosphorodiamidic acid 1 was developed as an efficient Br?nsted acid catalyst for the direct Mannich reaction of N-acyl imines with 1,3-dicarbonyl compounds. Phosphorodiamidic acids were proposed as a novel structural motif of enantioselective ­ Br?nsted acid catalysts because they possess unique features, including the capability of introducing various substituents to the nitrogen atoms and the preparation from readily available chiral diamines in a short step. We demonstrated that chiral phosphorodiamidic acid 1b derived from binaphthalene bis(sulfonamide) functioned as an enantioselective catalyst to give the Mannich product in an optically active form.