反应详情

A 1M solution of 1-(2-thienylthio)acetone (2.6 g, 15.1 mmol) in chlorobenzene (15 mL) was heated to 110° C. under nitrogen and hot polyphosphoric acid (3 mL) was added. The reaction was heated to reflux overnight. The chlorobenzene layer was decanted off and further chlorobenzene (15 mL x2) was added to the polyphosphoric acid residue and stirred at reflux for 30 minutes. The combined chlorobenzene extracts were concentrated in vacuo and purified by flash column chromatography on silica, eluting with 40% dichloromethane/isohexane, to give 3-methylthieno[2,3-b]thiophene (0.97 g, 42%). 1H NMR (500 MHz, CDCl3) δ 7.34 (1H, dd, J=1.0, 5.2 Hz), 7.16 (1H, d, J=5.2 Hz), 6.94 (1H, t, J=1.1 Hz), 2.40 (3H, d, J=1.1 Hz).

1. temperatureThe reaction was heated
2. temperatureto reflux overnight
3. customThe chlorobenzene layer was decanted off
4. additionfurther chlorobenzene (15 mL x2) was added to the polyphosphoric acid residue
5. temperatureat reflux for 30 minutes
6. concentrationThe combined chlorobenzene extracts were concentrated in vacuo
7. custompurified by flash column chromatography on silica
8. washeluting with 40% dichloromethane/isohexane