合成路线1

Synthesis of intermediate (II): 2) The esterification of penicillin G (XXI) with diphenylmetbanol and pyridine gives the corresponding ester (XXII), which is oxidized with H2O2 and formic acid to the sulfoxide (XXIII). The reaction of (XXIII) with trimethyl phosphite in refluxing toluene yields the bicyclic thiazoline (XXIV), which is ozonolyzed with O3 in methanol dichloromethane affording the enol (XXV). The condensation of (XXV) with morpholine by means of p-toluenesulfonyl chloride in THF gives the enamine (XXVI), which by bromination with Br2 in pyridine and hydrolysis with H2SO4 in aqueous methanol is converted to diphenylmethyl 7beta-(phenylacetylamino)-3-hydroxy 3-cephem 4-carboxylate (XXVIII) through the intermediate (XXVII).