134. Enantioselective systheses of α-amino acids from 10-sulfonamido-isobornyl esters and di-t-butyl azodicarboxylate
     Oppolzer, W.; Moretti, R.
     Tetrahedron 1988, 44, 5541-5552

Successive treatment of chiral esters 7 with LDA/Me₃SiCl and di-t-butyl azodicarboxylate/TiCl₄ and Ti(OiPr)₄ gave N,N-di-t-butoxycarbonylhydrazinoesters 11 which on deacylation, hydrogenolysis, transesterification and acidic hydrolysis furnished (2S)-α -amino acid hydrochlorides 13 in good overall yields, high enantiomeric purity and with efficient recovery of the alcohol auxiliary 4. Experimental evidence for the configuration and conformation of the intermediate O-silyl ketene acetals 1 is provided.

DOI : 10.1016/S0040-4020(01)86059-2