Cl.[NH:2]1[CH2:7][CH2:6][CH:5]([CH2:8][CH2:9][CH2:10][C:11]([OH:13])=[O:12])[CH2:4][CH2:3]1.[CH2:14]([O:21][C:22](Cl)=[O:23])[C:15]1[CH:20]=[CH:19][CH:18]=[CH:17][CH:16]=1>O.[OH-].[Na+]>[C:15]1([CH2:14][O:21][C:22]([N:2]2[CH2:7][CH2:6][CH:5]([CH2:8][CH2:9][CH2:10][C:11]([OH:13])=[O:12])[CH2:4][CH2:3]2)=[O:23])[CH:20]=[CH:19][CH:18]=[CH:17][CH:16]=1Either solid 4-(4-piperidyl) butyric acid hydrochloride (124 kg) is dissolved in water (600 kg), or the 16% aqueous solution of 4-(4-piperidyl)butyric acid hydrochloride prepared in step 3 (777 kg), is diluted with aqueous sodium hydroxide (289 kg) in a 1600 liter glass lined reactor cooled at 5° C. Benzylchloroformate (112 kg) is added over a period of 2-3 hours and the solution is heated to about 25° C. The reaction mixture is extracted with methyl tert-butyl ether (476 kg). The aqueous layer is then acidified with hydrochloric acid (187 kg) and extracted with toluene (450 kg). The organic layer is washed with water (240 kg) and dried by azeotropic distillation at atmospheric pressure under nitrogen. The resulting solution of 1-[(phenylmethoxy)carbonyl]-4-piperidinebutanoic acid in toluene is used as is in step 5. Weight of the product in solution: 179 kg. Quality: about 35% w/w in toluene.
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