| abstract |
Heterocyclic acetic acid derivatives of the general formula (I), <IMAGE> wherein Y<1> and Y<2> form together a removable carbonyl protecting group, and X is a selectively removable esterifying group, are prepared by esterifying a compound of the general formula (III), <IMAGE> wherein Y<1> and Y<2> are as defined above and R' is a removable amido protecting group other than phenyl group, and removing the protecting group R' of the resulting novel compound of the general formula (II), <IMAGE> wherein X, R', Y<1> and Y<2> are as defined above. The compounds of the general formula (I) are valuable intermediates of the synthesis of thienamycin and thienamycin analogues. |