CO[CH:3]1[CH2:7][CH2:6][CH:5](OC)[O:4]1.[CH2:10]([C:17](O)=O)[C:11](CC(O)=O)=O.[CH2:20]([NH2:27])[C:21]1[CH:26]=[CH:25][CH:24]=[CH:23][CH:22]=1.Cl>O>[CH2:20]([N:27]1[CH:6]2[CH2:5][CH2:17][CH:10]1[CH2:11][C:3](=[O:4])[CH2:7]2)[C:21]1[CH:26]=[CH:25][CH:24]=[CH:23][CH:22]=1This was prepared according to the reported method (Chem. Abs., 1958, 53, 432e). A mixture of 2,5-dimethoxytetrahydrofuran (13 ml, 0.1 mol), 2 drops of c-HCl and water (10 ml) was stirred at room temperature for 1 h, then treated with water(10 ml), acetone-1,3-dicarboxylic acid (14.6 g, 0.1 mol), and benzylamine (10.9 ml, 0.1 mol). After the initial foaming had subsided, the pH was adjusted to 5 with 1N HCl, and stirring was continued for 14 h. The reaction mixture was adjusted to pH 1, washed with ethyl acetate, filtered through celite, and then adjusted to pH 12 with NaOH, and extracted with ethyl acetate. The extract was dried over Na2SO4 and concentrated to afford 14.5 g (67% crude) of an oil, which was used for next reaction without further purification.
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