A new class of metal-free catalysts for direct diastereo- and regioselective Mannich reactions in aqueous media

Camphor sulfonic acid is an efficient catalyst for Mannich reactions of benzaldehyde, aniline and various ketones in aqueous media, with diastereo- or regioselectivities. Meanwhile, three sulfonated amino acids can catalyze the same type of reactions effectively with high diastereo- or regioselectivities.