Br[CH2:2][C:3]([O:5][CH2:6][CH3:7])=[O:4].C(N(CC)C(C)C)(C)C.[CH2:17]([NH2:24])[C:18]1[CH:23]=[CH:22][CH:21]=[CH:20][CH:19]=1.ClCCl>O1CCOCC1>[CH2:6]([O:5][C:3](=[O:4])[CH2:2][NH:24][CH2:17][C:18]1[CH:23]=[CH:22][CH:21]=[CH:20][CH:19]=1)[CH3:7]To a solution of ethyl bromoacetate (2.22 mL, 20.0 mmol) in 1,4-dioxane (40 mL) is added N,N-diisopropylethylamine (7.0 mL, 40.0 mol) and benzylamine (3.3 mL, 30.0 mmol), and the mixture is heated at 90° C. for 3 h. The reaction mixture is cooled to RT, dichloromethane is added, and the solution is washed with water, brine, then dried (MgSO4), and filtered. The filtrate is evaporated, and the residue is residue purified by chromatography on silica gel; elution with EtOAc:MeOH:heptane (35:5:60) gives 2.9 g of the product 421. 1H NMR (CDCl3) δ 7.4-7.3 (m, 6 H), 4.19 (q, 2 H), 3.80 (s, 2 H), 3.40 (s, 2 H), 1.25 (t, 3 H); MS: m/z 194 (M++1).
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