A solution of 1,1′-carbonyldiimidazole (151 mg, 0.934 mmol) and 4-(hexahydro-1,4-diazepin-5-on-1-yl)benzoic acid (219 mg, 0.934 mmol) in anhydrous N,N-dimethylformamide (7 mL) was stirred at 75° C. for 55 min. The mixture was allowed to cool, and a solution of (S)-3-amino-5-(4-methylpiperazin-1-yl)-3,4-dihydro-2H-1-benzopyran (210 mg, 0.85 mmol) in N,N-dimethylformamide (3.5 mL) was added. The reaction mixture was stirred at room temperature for 14 days. The solvent was removed in vacuo, and the residue was purified by column chromatography on silica (eluent: chloroform/ethanol, 90:10+1% conc. NH3). The product was crystallized from a mixture of chloroform, ethanol, and ethyl acetate affording 84 mg (21% yield) of the title compound as white crystals: mp 244-247° C. (decomposes); [α]21D −148° (c 0.50, chloroform); TSPMS (70 eV) m/z 464 (M+1).
