Organocatalyzed direct asymmetric alpha-halogenation of carbonyl compounds.

The formation of carbon-halogen bonds in an enantioselective manner is an important reaction because it leads to optically active halogen compounds, which are useful intermediates for further elaboration to other valuable compounds. Within the past few years various enantioselective alpha-halogenations of carbonyl compounds by asymmetric organocatalysis have been reported. Most importantly, these recent developments have greatly enhanced the synthetic utility of alpha-halogenations and opened up a promising new frontier in organic synthesis.