5H-Cyclopenta[c]pyridin-5-one,6,7-dihydro-(9CI)

Synthesis

19608-41-4

350847-80-2

General procedure for the synthesis of 6,7-dihydro-5H-cyclopentadieno[c]pyridin-5-one from methyl 3-(3-ethoxy-3-oxopropyl)isonicotinate: to a tetrahydrofuran (THF, 5.0 mL) solution of methyl 3-(3-ethoxy-3-oxopropyl)isonicotinate (300 mg, 1.26 mmol) was added potassium 2-methylpropan-2-ol ( 0.28 g, 2.52 mmol). The reaction mixture was stirred at room temperature for 1 hour. Subsequently, the solvent was evaporated to dryness. Concentrated hydrochloric acid (5 mL) was added to the residue and the reaction mixture was stirred at 100 °C for 2 hours. After continuing to stir at 100 °C for 16 h, saturated aqueous sodium bicarbonate (40 mL) and ethyl acetate (EtOAc, 50 mL) were added to the reaction vessel, and the resulting two-phase mixture was transferred to a partition funnel. The organic and aqueous layers were separated and the aqueous phase was extracted with ethyl acetate (2 x 50 mL). The organic phases were combined, washed with saturated saline, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure. The resulting oil was purified by fast column chromatography using isocratic elution conditions of ethyl acetate (35%) and hexane (65%) to afford 6,7-dihydro-5H-cyclopenta[c]pyridin-5-one (0.03 g, 0.23 mmol) as a gray oil.

References