Acetyl chloride → N-[2-(1,6,7,8-tetrahydro-2H-cyclopenta[b]furo[3,2-d]pyridin-8-yl)ethyl]acetamide

To a solution of (2E)-2-(1,2,6,7-tetrahydro-8H-cyclopenta[b]furo[3,2-d]pyridin-8-ylidene)ethanamine (186 mg, 0.920 mmol) in pyridine (3.7 mL) was added acetyl chloride (78.5 μL, 1.10 mmol) under ice-cooling, and the mixture was stirred for 10 min. The reaction solution was diluted with saturated aqueous sodium hydrogen carbonate solution, and the mixture was extracted with ethyl acetate. The extract was dried over anhydrous sodium sulfate. The solvent was evaporated under reduced pressure and the residue was purified by silica gel column chromatography (ethyl acetate/hexane=50/50→100/0). The residue was dissolved in methanol (1.1 mL), palladium-carbon powder (11 mg) was added, and the mixture was stirred at 50° C. for 3 hr under a hydrogen atmosphere. The catalyst was filtered off, and the filtrate was evaporated under reduced pressure. The residue was purified by silica gel column chromatography (ethyl acetate/hexane=90/10→100/0) to give the title compound (49.1 mg, yield 22%).