Acetic Anhydride → 1,3-Cyclopentanedicarboxylic anhydride

Beteiligte Stoffe

Reaktionsschritte

1,3-Cyclopentanedicarboxylic acid (4.0 g., 25 mmole) was converted to the anhydride by refluxing for 3 hours in 20 ml. of acetic anhydride. After removal of excess acetic anhydride, extraction with hexane and evaporation of the hexane, 3.95 g. of cyclopentane-1,3-dicarboxylic anhydride was obtained. The anhydride was combined with 6.51 g. (27 mmole) of 1-(4-aminobutyl)-4-(2-pyrimidinyl)piperazine in 50 ml. of dichloromethane and stirred at room temperature overnight. The dichloromethane was removed in vacuo and replaced with 75 ml. of toluene. The mixture was refluxed for 24 hours with water separation via a Dean-Stark trap. The product was concentrated under vacuum and chromatographed on 200 g. of silica gel with 5% ethanol/chloroform. The product-containing fractions were combined and concentrated and the residue crystallized (2 crops) from isopropanol with addition of 4N HCl/isopropanol. A second recrystallization from isopropanol gave 1.1 g. of the title compound as the dihydrochloride, hemihydrate; m.p. 201°-203° C.(d).

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