Thioester derivatives of thiazolyl acetic acid and their use in the preparation of cephalosporin compounds

摘要

The present invention provides new thioester derivatives of thiazolyl acetic acid of the general formula (I),wherein, R1 represents H, trityl, CH3, CRaRbCOOR2 (Ra and Rb independently of one another represents hydrogen or methyl and R2 represents H or C1-C4 alkyl).also, the invention provides a method by which the said thioester derivatives can be prepared by reacting thiazolyl acetic acid of the general formula (IV) with 1,2,5,6 tetrahdro-2-methyl-5,6 dioxo-1,2,4-triazin-3-thiol of the formula (VI) in asolvent, in presence of an organic base and with the help of Vilsmeier reagent of the formula (V). The so obtained thioester derivatives are reacted with 7-amino-cephem carboxylic acids of the general formula (III) to produce cephalosporin antibiotic compounds having the general formula (II).