Abstract: There is described a process for the preparation of 7-(D(-)-alpha-amino-p-hydroxyphenylacetamido)desacetoxycephalosporanic acid in which a D(-)-p-hydroxy-N-(1-alcoxycarbonyl-2-propenyl)-alpha-aminophenylacetic acid salt is reacted with trimethylsilyl-2-oxazolidinone. The resulting reaction product is reacted in turn with an acyl chloride or an alkyl chloroformate to give a mixed anhydride which is reacted with a solution of 7-aminodesacetoxycephalosporanic acid prepared by silylation, in an anhydrous organic solvent, with trimethylsilyl-2-oxazolidinone.

Abstract: The present invention is related to a process in which an oxazolidinone is reacted with phosphorus pentachloride and the resulting mixture is reacted with a nucleophilic agent in an inert solvent to give P-substituted N,N'-bis-(3-oxazolidinyl-2-one)phosphoramides having the general formula ##STR1## where R.sub.1, R.sub.2, R.sub.3, R.sub.4 are each a group selected from among hydrogen, C.sub.1 -C.sub.4 alkyls or an aromatic nucleus and X is a group which may be introduced by nucleophilic substitution. The invention is also related to the compounds thus obtained.