C(N(CC)CC)C.Cl.[CH2:9]([O:11][C:12](=[O:15])[CH2:13][NH2:14])[CH3:10].[OH:16][C@@H:17]([C:23]1[CH:28]=[CH:27][CH:26]=[CH:25][CH:24]=1)[C:18](=[CH2:22])[C:19](O)=[O:20].C1(N=C=NC2CCCCC2)CCCCC1>ClCCl>[CH2:9]([O:11][C:12](=[O:15])[CH2:13][NH:14][C:19](=[O:20])[C:18](=[CH2:22])[C@@H:17]([OH:16])[C:23]1[CH:24]=[CH:25][CH:26]=[CH:27][CH:28]=1)[CH3:10]
Triethylamine (3.75 mL, 0.027 mol, 1.2 eq) was added to a suspension of glycine ethyl ester hydrochloride (3.44 g, 0.024 mol, 1.1 eq) in anhydrous dichloromethane (60 mL) (see FIG. 4). The mixture was stirred for 15 min at room temperature and then cooled to 0° C. (ice bath). Compound 9a (4 g, 0.022 mol, 1 eq) and dicyclohexylcarbodiimide (5.09 g, 0.02469 mol, 1.1 eq) were added successively to the reaction mixture which was stirred at room temperature for 17 h. The precipitate (dicyclohexylurea and triethylamine hydrochloride) was collected by filtration. The filtrate was washed with a 1N aqueous solution of HCl (50 mL), brine (50 mL) and dried over sodium sulfate. Evaporation of the solvent afforded an oil which was purified by column chromatography (eluent: hexane/EtOAc=6:4). The desired product 10a was obtained as a yellow oil (3.51 g, 60%). Rf 0.25 (hexane/EtOAc=4:6). 1H NMR δ (CDCl3) 1.25 (t, 3H), 3.63 (s, 1H), 4.02 (m, 2H), 4.17 (q, 2H), 5.49 (s, 1H), 5.58 (d, 1H), 5.96 (s, 1H), 6.86 (s, 1H), 7.65 (m, 5H). [M+H]+ 264.1: tR=2.55 min; purity: 96%.
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