Synthesis of (6R,7R)-7-[2-(5-amino-1,2,4-[5-14C]thiadiazol-3-yl)-(Z)-2-methoxyiminoacetamidol[-3-([4-carbamoyl-1-quinuclidinio)methyl]ceph-3-em-4 -carboxylate ([14C]E1040)

(6R, 7R)-7-[2-(5-amino-1,2,4-thiadiazol-3-yl)-(Z)-2-methoxy-iminoacetamido]-3-[4-(carbamoyl-1-quinuclidinio)methyl]ceph-3-em-4-carboxylate (E1040), a new injectable cephalosporin with potent antipseudomonal activity, was synthesized labelled with carbon-14, starting from potassium [14C]thiocyanate with 2-(N-chloroamidino)-2-(methoxyimino)acetic acid (I) gave (5-amino-1,2,4-[5-14C] thiadiazol-3-yl-2-methoxyimino)acetic acid (II). 7-Amino-3-[(4-carbamoyl-1-quinuclidinio)methyl]ceph-3-em-4-carboxylate hydrochloride (IV) was acylated with the above acid chloride using the PC15 method, to afford the title compound (V); [14C]E1040, having a specific activity of 3.74 MBq/mg (as its anhydride), was obtained in 47% overall radiochemical yield, with a radiochemical purity of more than 98.1%. (author)