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 ...
[Krasnov, Victor P.; Levit, Galina L.; Bukrina, Iraida M.; Demin, Alexander M.; Chupakhin, Oleg N.; Yoo, Ji Uk Tetrahedron Asymmetry, 2002 , vol. 13, # 17 p. 1911 - 1914]