Ammonia → 4-(6-Fluoro-3,4-dimethoxyphenyl)-4,5,6,7-tetrahydrothieno[2,3-c]pyridine

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Reaction Conditions

Reaction Steps

A mixture of 0.66 g of α-[[(2-thenyl)amino]methyl]-6-fluoro-3,4-dimethoxybenzyl alcohol and 10 ml of polyphosphoric acid was stirred for 3.5 hours at 60° C. The reaction solution was poured into ice water, and the mixture was basified by addition of 25 ml of conc. aqueous ammonia. The mixture was extracted with chloroform, and the chloroform layer was washed with water, and dried over anhydrous magnesium sulfate. The solvent was distilled off, and 0.66 g of 4-(6-fluoro-3,4-dimethoxyphenyl)-4,5,6,7-tetrahydrothieno[2,3-c]pyridine was obtained as a syrupy matter. (2) 0.65 g of 4-(6-fluoro-3,4-dimethoxyphenyl)-4,5,6,7-tetrahydrothieno[2,3-c]pyridine was dissolved in 14 ml of dichloromethane; and to the mixture was added 1M boron tribomide-dichloromethane solution (12 ml) dropwise under an argon gas stream, while cooling at -30°--60° C. (internal temperature) while stirring. The mixture was stirred for 2 hours at room temperature, and 20 ml of methanol was added dropwise thereto under ice cooling. The solvent was distilled off, and the residue obtained was crystallized by using a mixture of methanol and chloroform (1:8). The crystals were collected by filtration, and recystallized from ethanol, giving 0.29 g 0f 4-(6-fluoro-3,4-dihydroxyphenyl)-4,5,6,7-tetrahydrothieno[2,3-c]pyridine hydrobromide.

Provenance & Evidence