[CH3:1][O:2][C:3]([CH2:5][CH2:6][CH:7]([CH3:11])[C:8]([OH:10])=O)=[O:4].[CH2:12]([O:19][C:20](=[O:24])[C@H:21]([CH3:23])[NH2:22])[C:13]1[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=1.OC1C2N=NNC=2C=CC=1.C1(N=C=NC2CCCCC2)CCCCC1>ClCCl>[CH2:12]([O:19][C:20](=[O:24])[C@H:21]([CH3:23])[NH:22][C:8](=[O:10])[CH:7]([CH3:11])[CH2:6][CH2:5][C:3]([O:2][CH3:1])=[O:4])[C:13]1[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=14-methoxycarbonyl-2-methylbutanoic acid (3.1 g.), L-alanine benzyl ester (3.58 g.) and hydroxybenzotriazole (2.7 g.) are dissolved in dichloromethane. The solution is chilled in the ice bath and dicyclohexylcarbodiimide (4.12 g.) is added. After stirring 15 minutes in the ice bath and 18 hours at room temperature the precipitate is filtered off and the filtrate is concentrated to dryness. The residue is dissolved in ethyl acetate and washed neutral. The organic phase is dried over magnesium sulfate and concentrated to dryness to yield N-(4-methoxycarbonyl-2-methylbutanoyl)-L-alanine benzyl ester.
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