[CH3:1][P:2](Cl)([C:4]1[CH:9]=[CH:8][CH:7]=[CH:6][CH:5]=1)=[O:3].[CH3:11][O:12][C:13](=[O:23])[C@@H:14]([CH3:22])[NH:15][CH2:16][CH2:17][CH2:18][CH2:19][CH2:20][CH3:21].C(N(CC)CC)C>ClCCl.CN(C)C1C=CN=CC=1>[CH3:11][O:12][C:13](=[O:23])[C@@H:14]([CH3:22])[N:15]([P@@:2]([CH3:1])([C:4]1[CH:9]=[CH:8][CH:7]=[CH:6][CH:5]=1)=[O:3])[CH2:16][CH2:17][CH2:18][CH2:19][CH2:20][CH3:21]Methylphenyl-phosphinic chloride (1.05 g, 6 mmol) is dissolved in dichloromethane (50 mL) and cooled to 0° C. To this is added a solution of N-hexyl-D-alanine methyl ester (1 g, 5.34 mmol) and triethylamine (2.1 mL, 15 mmol) in dichloromethane (10 mL). A catalytic amount of 4-dimethylaminopyridine is added and reaction is stirred for 16 hours, washed with water and brine, dried over sodium sulfate, and concentrated. The crude product is purified by silica gel flash chromatography (100% ethyl acetate) to give N-((R)-methylphenylphosphinyl)-N-hexyl-D-alanine methyl ester as an oil.
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