C1(CC([NH:10][CH:11]2[C:31](=[O:32])[N:13]3[C:14]([C:18]([O:20][CH2:21][C:22]4[CH:27]=[CH:26][C:25]([N+:28]([O-:30])=[O:29])=[CH:24][CH:23]=4)=[O:19])=[CH:15][CH2:16][S:17][C@H:12]23)=O)C=CC=CC=1.N1C=CC=CC=1.P(Cl)(Cl)(Cl)(Cl)Cl.CO>ClCCl>[NH2:10][CH:11]1[C:31](=[O:32])[N:13]2[C:14]([C:18]([O:20][CH2:21][C:22]3[CH:23]=[CH:24][C:25]([N+:28]([O-:30])=[O:29])=[CH:26][CH:27]=3)=[O:19])=[CH:15][CH2:16][S:17][C@H:12]12To a suspension of p-nitrobenzyl 7-phenylacetamido-3-cephem-4-carboxylate (10.50 g.) in dry dichloromethane (100 ml.) was added dry pyridine (2.14 g.). Phosphorus pentachloride (5.50 g.) was added to the solution at -10° C., and the mixture was stirred at -5° C. for 45 minutes and further at 10° C. for an hour. After adding methanol (520 g.) to the resultant mixture, the mixture was stirred at -20° C. for 1.5 hours. The precipitates were collected by filtration, washed with dichloromethane (120 ml.) and diethyl ether (130 ml.) in turn, and then dried to give p-nitrobenzyl 7-amino-3-cephem-4-carboxylate (7.90 g.), m.p. 182° C. (dec.).
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