Formaldehyde → 1,2,3,4-Tetrahydro[1]benzothieno[2,3-c]pyridine

Participants

Reaction Steps

A mixture of 2-(benzo[b]thien-3-yl)ethylamine hydrochloride (0.5 g, 2.34 mmol) and paraformaldehyde (0.125 g, 4.16 mmol) in methanol (15 mL) was refluxed for 24 h. The reaction mixture was concentrated under reduce pressure and the residue was neutralized with saturated NaHCO3 (50 mL), and extracted with ethyl acetate (2×50 mL). The organic layer was dried over anhydrous sodium sulfate, filtered and concentrated to furnish 1,2,3,4-tetrahydro[1]benzothieno[2,3-c]pyridine (160 mg, 35%); 1H NMR (200 MHz, CDCl3): δ 2.81 (m, 2H), 3.25 (m, 2H), 4.15 (s,2H), 7.30 (m, 2H), 7.69 (d, J=4.0 Hz, 1H), 7.79 ((d, J=4.0 Hz, 1H).

Provenance & Evidence