We have developed a new method for the stereospecific synthesis of enantiomers of acid I that is based on the use of glutamic acid derivatives that have genuine L or D configurations of the a-carbon atom. As the starting compound for the synthesis we used dimethyl esters of N-phthalyl-4-bromo-L-or D-glutamic acids (IVa, b), which were obtained by a method similar to that in [9] and were hydrolyzed with 20% HCI.
