N1C=CC=CC=1.[C:7]1([CH2:13][C:14](Cl)=[O:15])[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=1.[C:17]1([CH:23]([O:30][C:31]([C:33]2[N:38]3[C:39](=[O:42])[C@@H:40]([NH2:41])[C@H:37]3[S:36][CH2:35][C:34]=2[O:43][CH3:44])=[O:32])[C:24]2[CH:29]=[CH:28][CH:27]=[CH:26][CH:25]=2)[CH:22]=[CH:21][CH:20]=[CH:19][CH:18]=1>CCl>[C:17]1([CH:23]([O:30][C:31]([C:33]2[N:38]3[C:39](=[O:42])[C@@H:40]([NH:41][C:14](=[O:15])[CH2:13][C:7]4[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=4)[C@H:37]3[S:36][CH2:35][C:34]=2[O:43][CH3:44])=[O:32])[C:24]2[CH:25]=[CH:26][CH:27]=[CH:28][CH:29]=2)[CH:22]=[CH:21][CH:20]=[CH:19][CH:18]=11 ml of pyridine and 0.5 ml of phenylacetic acid chloride are added at 0° C, under a nitrogen atmosphere, to a suspension of 0.250 g of 7β-amino-3-methoxy-3-cephem-4-carboxylic acid diphenylmethyl ester in 25 ml of methyl chloride and the mixture is stirred for 30 minutes at this temperature. The reaction mixture is evaporated under reduced pressure; the residue is stirred for 10 minutes with 20 ml of a 1:1 mixture of dioxane and water and diluted with methylene chloride. The aqueous phase is separated off and extracted with methylene chloride. The combined organic phases are washed with a saturated aqueous sodium bicarbonate solution and a saturated aqueous sodium chloride solution, dried over sodium sulphate and evaporated under reduced pressure. The crude product is purified by means of preparative thin layer chromatography using, as the solvent, a 1:1 mixture of toluene and ethyl acetate. The zone visible under ultraviolet light of λ = 254 mμ (Rf~0.35) is eluted with a 4:1 mixture of acetone and methanol and gives 3-methoxy-7β-(α-phenylacetylamino)-3-cephem-4-carboxylic acid diphenylmethyl ester which is identical with the product obtainable by the process of Example 9.
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