Facile synthesis of l-Dopa tert-butyl ester by catalytic enantioselective phase-transfer alkylation

Facile asymmetric synthesis of l-Dopa and related amino acid esters has been achieved by phase-transfer catalysis of the rationally designed C2-symmetric chiral quaternary ammonium salts 1. The ‘scale-up’ experiment performed with 5.00 g of tert-butyl glycinate-benzophenone Schiff base (2) represents the practical aspect of our approach.