Hydrochloric Acid → 6.7-dihydrothieno[3.2.c]pyridin-4(5H)-one

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Reaction Steps

An initially heterogeneous mixture of 4-oxo-5-acetyl-4,5,6,7-tetrahydro-thieno[3,2-c]pyridine (13.6 g; 0.069 mole) from Example 5, ethanol (50 ml) and 6 N hydrochloric acid (50 ml) is stirred for 4 hours at room temperature. The reaction mixture is concentrated in vacuo, the residue is made slightly basic by addition of sodium hydroxide and is then extracted with methylene chloride. The organic extracts are washed with water, dried over sodium sulfate and evaporated to dryness. The resulting residue is recrystallized from isopropanol-diisopropyl ether, to give white crystals, M.p.=94° C. Yield: 70%.

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