In order to synthesize four stereoisomers of cystathionine (CYT), D-and L-homocysteines (D- and L-Hcy) were synthesized from methionine (Met) by a facile procedure. L-Met was reacted with dichloroacetic acid in concentrated hydrochloric acid under reflux to give (4S)- 1, 3-thiazane-2, 4-dicarboxylic acid hydrochloride [(4S)-TDC· HCl]. L-Hcy was obtained by treatment of (4S)-TDC· HCl with hydroxylamine. D-Hcy was also synthesized from D-Met ...