Potassium Carbonate → Ethyl 2-ethyl-8,9-dihydrofuro[3,2-c]pyrazolo[1,5-a]pyridine-1-carboxylate

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Reaction Steps

To a mixture of 5-amino-2,3-dihydrofuro[3,2-c]pyridin-5-ium 2,4-dinitrobenzenolate (8.00 g, 25.0 mmol) and potassium carbonate (4.84 g, 35.0 mmol) in dimethylformamide (100 mL) was added ethyl 2-pentynoate (3.63 mL, 27.5 mmol) under ice-cooling, and the mixture was stirred at room temperature for 20 hr. The reaction solution was diluted with water and 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=10/90→40/60) to give the title compound (794 mg, yield 12%).

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