Reaction SMILES: ClCC(NC1SC=C(/C(=N/OC)/C(N[C@@H:15]2[C:22](=[O:23])[N:21]3[C@@H:16]2[S:17][CH2:18][C:19]([CH2:27]SC2N(C)N=C(O)C(=O)N=2)=[C:20]3[C:24]([OH:26])=[O:25])=O)N=1)=O.NC(N)=S.[C:45](=[O:48])([O-])[OH:46].[Na+].[CH:50](O)=O>O>[CH3:50][C:45]([O:46][CH2:27][C:19]1[CH2:18][S:17][C@@H:16]2[CH2:15][C:22](=[O:23])[N:21]2[C:20]=1[C:24]([OH:26])=[O:25])=[O:48]
Reactant: CO/N=C(\C(=O)N[C@@H]1C(=O)N2C(C(=O)O)=C(CSc3nc(=O)c(O)nn3C)CS[C@H]12)c1csc(NC(=O)CCl)n1
Reactant: O=CO
Reactant: O=C([O-])O
Agent: NC(N)=S
Agent: [Na+]
Solvent: O
Product: CC(=O)OCC1=C(C(=O)O)N2C(=O)C[C@H]2SC1
Reaction time: 8 h

Procedure:
15.3 g of (6R,7R)-7-[2-[2-(2-chloroacetamido)-4-thiazolyl]-2-[(Z)-methoxyimino]acetamido]-3-[[(2,5-dihydro-6-hydroxy-2-methyl-5-oxo-as-triazin-3-yl)thio]methyl]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid (Fraction I) are suspended in 150 ml of water together with 5 g of thiourea. While gassing well with nitrogen and stirring, the pH is adjusted to 6.8-7.0 with saturated sodium hydrogen carbonate solution, an orange coloured solution resulting. The pH of the solution is held constant at 6.8 for 6 hours by means of an autotitrator with the addition of sodium hydrogen carbonate solution. A further 2.5 g of thiourea are added and the solution is stirred for a further 3 hours, the pH being held at 6.8 with the addition of saturated sodium hydrogen carbonate solution. The red solution is stored overnight in a refrigerator, the solution becoming darker. The pH of the solution is adjusted to 2.0-2.5 by the addition of 100% formic acid, a substance separating. This substance is filtered off under suction and washed with 100 ml of 10% aqueous formic acid. The mother liquor is discarded. The brownish material on the suction filter is suspended in 200 ml of water and the pH is adjusted to 7 with triethylamine, a brown solution resulting. This solution is stirred with 2 g of active carbon for 30 minutes, the carbon is filtered off and the still brown filtrate is adjusted to pH 3.5 with 100% formic acid while stirring well. The substance which thereby separates is filtered off under suction, washed with 50 ml of 10% aqueous formic acid and discarded. The dark yellow filtrate is adjusted to pH 2-2.5 with 100% formic acid, a substance separating. This substance is filtered off under suction, washed with ice/water and dried. The cephalosporanic acid obtained is converted into the disodium salt by suspension in a mixture of 40 ml of acetone and 40 ml of water and treatment with 20 ml of a 2 N solution of 2-ethylcaproic acid sodium salt in ethyl acetate. To the thereby resulting orange coloured solution are added 50 ml of acetone, there separating a brown resin which is filtered off. The yellow filtrate is stirred for 30 minutes, the disodium salt crystallising. The mixture is treated portionwise with a further 50 ml of acetone and stored overnight in a refrigerator. The crystallisate is filtered off under suction, washed successively with acetone/water (85:15), pure acetone and low-boiling petroleum ether and dried at 40° C. overnight in vacuo. There is obtained the disodium salt of (6R,7R)-7-[2-(2-amino-4-thiazolyl)-2-[(Z)-methoxyimino]acetamido]-3-[[(2,5-dihydro-6-hydroxy-2-methyl-5-oxo-as-triazin-3-yl)thio]methyl]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid in the form of beige coloured crystals; [α]D20 =-144° (c=0.5 in water). The nuclear magnetic resonance spectrum and the microanalysis correspond to the given structure.