Sodium Sulfide → Methyl 4,6-dihydrothieno[3,4-b]thiophene-2-carboxylate

Participants

Reaction Steps

A solution of 4.8 g (20 mmol) (2) in 240 mL methanol was heated up and kept mild boiling. Sodium sulfide solution (1.7 g, 22 mmol) in 160 mL methanol was added dropwise in 2 h. After cooling of the reaction mixture, the precipitate was filtered off. The solvent was removed by evaporation and the residue was washed by water. Column chromatography on silica gel using dichloromethane yielded the pure title compound as a white solid 2.0 g (50%). 1HNMR (CDCl3): δ 3.87 (3H, s), 4.05-4.06 (2H, t, J=3 Hz), 4.19-4.20 (2H, t, J=3 Hz), 7.48 (1H, s). 13CNMR (CDCl3): δ33.12, 33.47, 52.19, 127.90, 137.30, 143.90, 146.64, 162.51.

Provenance & Evidence