Asymmetric catalytic aza-Henry reactions leading to 1,2-diamines and 1-,2-diaminocarboxylic acids

In the wake of the aldol and Mannich reactions, textbook examples of asymmetric reactions, comes the aza-Henry reaction (aka nitro-Mannich reaction), which leads to 1,2-diamines or α,β-diaminocarboxylic acids (see scheme, PG= protecting group). Recent developments point to a bright future for this transformation.