[C:1]([N@@:20]1[CH2:22][CH:21]1[C:23]([O:25][CH3:26])=[O:24])(C1C=CC=CC=1)(C1C=CC=CC=1)[C:2]1C=CC=CC=1.C(O)(C(F)(F)F)=[O:28].CCN(CC)CC.C(Cl)(C)=O>CO.C(Cl)(Cl)Cl>[C:1]([N@@:20]1[CH2:22][CH:21]1[C:23]([O:25][CH3:26])=[O:24])(=[O:28])[CH3:2](P. Davoli et al., Tetrahedron: Asym. 1995, 6, 2011-2016). (R)-Methyl 1-tritylaziridine-2-carboxylate (9.00 g, 26.24 mmol) was dissolved in MeOH/CHCl3 (1:1, 90 mL) and cooled to 0° C. under Ar and TFA (15.15 mL, 196.80 mmol) was added dropwise. After the reaction mixture was allowed to stir at 0° C. (2 h), the solvent was evaporated in vacuo. The product was dissolved in CH2Cl2 (120 mL), cooled to 0° C., and Et3N (18.29 mL, 131.20 mmol) and AcCl (2.04 mL, 28.86 mmol) were added in two portions over 5 min. The solution was stirred at 0° C. (1 h) and then washed with saturated aqueous NaHCO3 (100 mL) and saturated aqueous brine (100 mL). The organic layer was dried (Na2SO4) and evaporated in vacuo, and then the crude product was purified by column chromatography (SiO2; 1/1 EtOAc/hexanes) and crystallized (cold hexanes) to yield 2.46 g (66%) of desired product as a clear crystal: mp 39-40° C.; [α]25D +84.3° (c 1.2, CHCl3); Rf=0.30 (1/2 EtOAc/hexanes); 1H NMR (CDCl3) δ 2.16 (s, CH3C(O)), 2.51 (dd, J=1.8, 5.5 Hz, NCHH′CH), 2.58 (dd, J=1.8, 3.0 Hz, NCHH′CH), 3.16 (dd, J=3.0, 5.5 Hz, CHH′CHN), 3.80 (s, OCH3); 13C NMR (CDCl3) δ 23.7 (CH3C(O)), 30.9 (NCH2CH), 34.4 (CH2CHN), 52.9 (OCH3), 168.9 (C(O)O), 180.6 (C(O)N); HRMS (ESI) 166.0474 [M+Na+] (calcd. for C6H9NO3Na 166.0480).
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