The Mannich reaction is a fundamental carbon−carbon bond-forming reaction in organic synthesis, 1 and a variety of nitrogen-containing pharmaceuticals and bioactive molecules such as β-amino acids and β-lactams are synthesized by this reaction. Recently, catalytic enantioselective Mannich reactions have been dramatically developed, and they offer a practically useful method for the preparation of optically active amino compounds. 2,3 However, inherent weak ...
