Formaldehyde → tert-butyl 4,5-Dihydrothieno[2,3-c]pyridine-6(7H)-carboxylate

Participants

Reaction Steps

A solution of 1.753 g (7.711 mmol) of N-tert-butoxycarbonyl-2-(3-thienyl)ethylamine, 0.46 g (15.4 mmol) of powdered paraformaldehyde and 73 mg (0.39 mmol) of p-toluenesulfonic acid monohydrate in 150 ml of toluene was refluxed under dehydrating conditions for 0.5 hours in a Dean-Stark trap. The reaction mixture was cooled to room temperature and diluted with ethyl acetate, after which it was washed with aqueous sodium hydrogen carbonate; the organic layer was dried over anhydrous magnesium sulfate; the solvent was distilled off under reduced pressure. The resulting crude product was purified by silica gel column chromatography (hexane/ethyl acetate=15/1 to 9/1) to yield the desired product.

Provenance & Evidence