Preparation of both enantiomers of β2-(3,4-dihydroxybenzyl)-β-alanine, higher homologues of Dopa

β2-(3,4-Dihydroxybenzyl)-β-alanine [β2-Homo-Dopa, ] is a novel β-amino acid homologue of Dopa, the most successful therapeutic agent in the treatment of Parkinsonʹs disease. Enantioenriched and were obtained via the diastereoselective alkylation of enantiopure pyrimidinone (R)- and , chiral derivatives of β-alanine, with veratryl iodide. The major diastereomeric products and were hydrolyzed with 57% HBr, and the desired β-amino acids were purified by silica gel chromatography. Alternatively, enantioenriched (R)- and were prepared by means of the highly diastereoselective alkylation (3,4-dimethoxybenzyl iodide) of open-chain β-aminopropionic acid derivatives and containing the chiral auxiliary α-phenylethylamine. Finally, nearly enantiopure (R)- and were obtained by resolution of racemic N-benzyloxycarbonyl-2-(3,4-dibenzyloxybenzyl)-3-aminopropionic acid, , with (R)- or (S)-α-phenylethylamine, followed by catalytic hydrogenolysis.