Phosphorus oxychloride → Ethyl 3-methyl-7-chlorothieno[3,2-b)pyridine-6-carboxylate

Participants

Reaction Steps

3-Methyl-6-ethoxycarbonylthieno[3,2-b]pyridin-7(4H)-one (7.0 g, 0.0295 mol) and phosphorus oxychloride (35 ml) were heated under reflux for 2 hours. The excess phosphorus oxychloride was removed by distillation under reduced pressure. The residue was poured onto ice, basified with 2N.NaOH and extracted with chloroform (3×100 ml). The combined chloroform extracts were washed with water, dried and evaporated to dryness to give a buff-coloured solid. This was collected, washed with petroleum ether (b.p. 40°-60°) and dried to give ethyl 3-methyl-7-chlorothieno[3,2-b]pyridine-6-carboxylate, 6.8 g, m.p. 113°-115°.

Provenance & Evidence