SYNTHESIS OF [C-14] E1077, A NOVEL PARENTERAL CEPHALOSPORIN ANTIBIOTIC

-[(6R,7R)-7-[(Z)-2-(5-amino-1,2,4-thiadiazol-3-yl) - 2- fluoromethoxyi minoacetamide] - 2 - carboxy - 8 - oxo- 5- 4.2.0]oct-2-ene-3-yl]-2-pro penyl](carbamoylmethyl) ethylmethylammonium hydroxide inner salt (E107 7), a new parenteral cephalosporin with well-balanced antibacterial sp ectrum and potent antibacterial activity, was labelled with carbon-14, starting from potassium [C-14]thiocyanate which on reaction with (Z) - 2 - (N - chloroamidino) - 2 - fluoromethoxyiminoacetic acid (I) gave 5-C-14]thiadiazol-3-yl)-2-fluoromethoxyiminoacetic acid (II). (RS) - [(E) - 3 - [(6R,7R) -7-Amino- 2 - carboxy - 8 oxo- 5- 4.2.0]oct-2-ene- 3-yl]-2-propenyl](carbamoylmethyl) ethylmethylammonium hydroxide inner salt (III) was acylated with the above acid using the POCl3-DMF metho d, to afford the title compound (IV); [C-14]E1077, having a specific a ctivity of 3.36 MBq/mg, was obtained in 50.3 % overall radiochemical y ield, with a radiochemical purity of more than 97.1 %.