C(N(CC)CC)C.Cl.[CH2:9]([O:11][C:12](=[O:15])[CH2:13][NH2:14])[CH3:10].[CH2:16]=[C:17]([CH2:21][C:22]1[CH:27]=[CH:26][CH:25]=[CH:24][CH:23]=1)[C:18](O)=[O:19].C1(N=C=NC2CCCCC2)CCCCC1>ClCCl>[CH2:9]([O:11][C:12](=[O:15])[CH2:13][NH:14][C:18](=[O:19])[C:17](=[CH2:16])[CH2:21][C:22]1[CH:27]=[CH:26][CH:25]=[CH:24][CH:23]=1)[CH3:10]Triethylamine (3.10 mL, 0.022 mol, 1.2 eq) was added to a suspension of glycine ethyl ester hydrochloride (2.84 g, 0.020 mol, 1.1 eq) in anhydrous dichloromethane (100 mL) (see FIG. 6). The mixture was stirred for 15 min at room temperature and then cooled to 0° C. (ice bath). Compound 17 (3 g, 0.018 mol, 1 eq) and dicyclohexylcarbodiimide (4.19 g, 0.020 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 successively with a saturated aqueous solution of sodium bicarbonate (100 mL), 1N aqueous solution of HCl (100 mL), brine (100 mL) and was then dried over sodium sulfate. Evaporation of the solvent afforded an oil which was purified by column chromatography (eluent:hexane/EtOAc=8:2). The desired product 18 was obtained as a solid (3.79 g, 83%). Rf=0.14 (hexane/EtOAc=7:3). m.p. 51° C. 1H NMR δ (CDCl3) 1.25 (t, 3H), 3.65 (s, 2H), 4.05 (d, 2H), 4.20 (q, 2H), 5.30 (s, 1H), 5.85 (s, 1H), 6.30 (s, 1H), 7.15–7.35 (m, 5H). [M+H]+ 248.0, tR=3.03 min; purity: 99.5%.
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