Cl.[C:2](=[NH:9])(OC)[CH2:3][CH2:4][CH2:5][CH3:6].CN(C)C=O.[NH2:15][CH2:16][C:17]1[CH:25]=[CH:24][C:20]([C:21]([OH:23])=[O:22])=[CH:19][CH:18]=1>C(N(CC)CC)C>[NH:9]=[C:2]([NH:15][CH2:16][C:17]1[CH:18]=[CH:19][C:20]([C:21]([OH:23])=[O:22])=[CH:24][CH:25]=1)[CH2:3][CH2:4][CH2:5][CH3:6]A 22 L, three-necked round bottom flask equipped with an air-powered mechanical stirrer was placed under a nitrogen atmosphere. The vessel was charged with methyl valerimidate hydrochloride (2.5 kg, 16 mol) and dimethylformamide (9.2 L). A thermometer was attached and the suspension cooled to 0°-15° C. with a cooling bath. Triethylamine (2.3 L) was added to the reaction at such a rate so that the internal temperature did not exceed 25° C. The cooling was stopped and the reaction was allowed to stir 1 hour. The reaction mixture was vacuum filtered using a Buchner funnel and a carboy (20 L). The filter cake was washed with additional dimethylformamide (1.0 L) and force-air dried for 15 min. The combined filtrates were saved. Another clean 22 L, three-necked round bottom flask equipped as above was placed under nitrogen. The vessel was charged with the combined filtrates from above followed by triethylamine (1.6 L) and 4-(aminomethyl)benzoic acid (1.7 kg, 11.5 mol). The thermometer was attached and the suspension was heated to an internal temperature of 65° C. with a heating mantle and a temperature controller. The heating was continued for 20 hours. The reaction was cooled to ambient temperature and filtered to yield 2.5 kg of product; 92% uncorrected yield.
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