Phosphorus oxychloride → 4-Chlorothieno[3,2-c]pyridine

Participants

Reaction Steps

Finely divided 4-oxo-4,5-dihydrothieno[3,2-c]pyridine (105.6 g, 0.69 mole) was stirred while being treated dropwise with phosphorus oxychloride (321.5 g, 2.1 mole) at 0°. The reaction mixture was then refluxed for 2.5 hours, cooled, and cautiously poured onto crushed ice (1000 mL). The resulting solution was stirred for 30 minutes and extracted with dichloromethane (3×400 mL). The organic portions were combined, dried (MgSO4), filtered, and concentrated in vacuo to a solid which was recrystallized from acetonitrile (400 mL) affording 101 g (85%) of light yellow solid, m.p. 91°.

Provenance & Evidence