| abstract |
A novel process for preparing cephem derivatives is characterized in that an acylating agent, <IMAGE> wherein R<3> is benzotriazolyl, pyridyl, succinimidyl or phthalimidyl, and n is 1 or 2, is used in esterifying 2-(2-amino-thiazol-4-yl)-2-syn-methoxyiminoacetic acid: <IMAGE> The ester thus obtained is then reacted with 7-aminocephalosporanic acid of formula III below to give a desired cephem derivative. Use of such an acylating agent eliminates the awkward steps of protection and then deprotection of the amino radical of the starting organic acid. <IMAGE> wherein R' is H or alkali metal and R<2> is H, acetoxymethyl or heterocyclicthiomethyl. |