Asymmetric synthesis of L-carbidopa based on a highly enantioselective α-amination.

A stereoselective synthesis of L-carbidopa in seven steps and 50% overall yield from commercial compounds is described. The key step involves a highly enantioselective α-amination reaction of an acyclic β-ketoester with di-tert-butyl azodicarboxylate induced by europium and (R,R)-diphenyl-pybox.