Reaktion #10321

Reaktionsgleichung

1-(2-thienylthio)acetone

→

3-methylthieno[2,3-b]thiophene

Ausbeute 42.0%

Lösungsmittel

chlorobenzene

Reaktionsbedingungen

Aufarbeitung

1. 1
   TemperaturThe reaction was heated
2. 2
   Temperaturto reflux overnight
3. 3
   SonstigeThe chlorobenzene layer was decanted off
4. 4
   workup.ADDITIONfurther chlorobenzene (15 mL x2) was added to the polyphosphoric acid residue
5. 5
   Temperaturat reflux for 30 minutes
6. 6
   EinengenThe combined chlorobenzene extracts were concentrated in vacuo
7. 7
   Sonstigepurified by flash column chromatography on silica
8. 8
   Wascheneluting with 40% dichloromethane/isohexane

Vorschrift

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).

Quelle