ASYMMETRIC SYNTHESIS OF R-β-AMINO BUTANOIC ACID AND S-β-TYROSINE: HOMOCHIRAL LITHIUM AMIDE EQUIVALENTS FOR MICHAEL ADDITIONS TO α,β-UNSATURATED ESTERS.

Article abstract of DOI:10.1016/S0957-4166(00)82354-X

Michael addition of the lithium amide derived from R-N-(α-methylbenzyl)benzylamine to benzyl E-crotonate is highly stereoselective (95percent d.e.) giving after debenzylation and crystallisation homochiral R-β-amino butanoic acid.A similar addition to methyl E-(p-benzyloxy)cinnamate is completely stereoselective giving after debenzylation and acid hydrolysis homochiral S-β-tyrosine as its HCl salt.