Cl[S:2]([N:5]=[C:6]=[O:7])(=[O:4])=[O:3].[C:8]1([CH2:14][OH:15])[CH:13]=[CH:12][CH:11]=[CH:10][CH:9]=1.Cl.[CH3:17][O:18][C:19](=[O:26])[C:20]([CH2:23][CH2:24][CH3:25])(C)[NH2:21].C(N(CC)CC)C.Cl.[Cl-].[Na+]>C(Cl)Cl>[CH3:17][O:18][C:19](=[O:26])[CH:20]([NH:21][S:2]([NH:5][C:6]([O:15][CH2:14][C:8]1[CH:13]=[CH:12][CH:11]=[CH:10][CH:9]=1)=[O:7])(=[O:4])=[O:3])[CH2:23][CH2:24][CH3:25]To a stirred solution of 15.4 9 ml (0. 178 mol) of chlorosulfonyl isocyanate in methylene chloride was added phenylmethanol (18.5 ml, 0.178 mol) at 0°-5° C. After stirring the above cold solution at this temperature, a solution of 34.9 g (0.192 mol) of 2-propyl-DL-alanine methyl ester hydrochloride in 350 ml of methylene chloride containing triethylamine (73.86 ml, 0.532 mol) was added, and the resulting mixture was stirred for 17 hours allowing the mixture to warm to room temperature. To the reaction mixture was added 500 ml of 10% aq. HCl solution saturated with sodium chloride, and the organic layer was separated. The aqueous layer was extracted with methylene chloride (2×100 ml) and the combined organic layer was dried over magnesium sulfate, concentrated in vacuo, and the residual brown oil was purified by flash chromatography (30% ethyl acetate in hexane) followed by crystallization from ether/hexane to afford 22.35 g (35%) of N-(carbobenzyloxyaminosulfonyl)-2-propyl-DL-alanine methyl ester (Formula XIV: R=CH3 ; R1 =propyl; R2 =CH3 ; R3 =H) as a white solid, m.p. 97°-99° C.
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