Phosphorodiamidic acid as a novel structural motif of Bronsted acid catalysts for direct Mannich reaction of N-acyl imines with 1,3-dicarbonyl compounds

Phosphorodiamidic acid 1 was developed as an efficient Bronsted 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 Bronsted 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.