The protection of 7-aminocephalosporanic acid (I) with di-tert-butyl dicarbonate gives 7-(tert-butoxycarbonylamino)cephalosporanic acid (II), which is condensed with 2,3-cyclopentenopyridine (III) by means of KI and NaHCO3 in hot water affording 7-(tert-butoxycarbonylamino)-3-[(2,3-cyclopenteno-1-pyridinium)methyl]ceph-3-em-4-carboxylate (IV). Deprotection of (IV) with trifluoroacetic acid anisole gives 7-amino-3-[(2,3-cyclopenteno-1-pyridinium)methyl]ceph-3-em-4-carboxylate (V), which is finally condensed with 2-(2-aminothiazol-4-yl)-2-syn-methoxyiminoacetic acid (VI) by means of phosgene in toluene.
By condensation of (III) with 7-[2-syn-methoxyimino-2-(2-aminothiazo)-4-yl(acetamido]cephalosporanic acid (VII) with KI and NaHCO3.