Phosphorus oxychloride → Methyl 3-chlorothieno[2,3-b]pyrazine-6-carboxylate

Participants

Reaction Steps

A mixture of 91 (6.66 mmol, 1.4 g) in phosphorus oxychloride (21.46 mmol, 2 mL) was heated to reflux for 5 days. Reaction mixture was concentrated under reduced pressure and co-evaporated with toluene (3×). The crude product was purified by chromatography (heptane/ethyl acetate 9/1) to give methyl 3-chlorothieno[2,3-b]pyrazine-6-carboxylate 92 (0.6 g, 40%). NMR (400 MHz, CDCl3) 4.01 (s, 3H), 8.18 (s, 1H), 8.71 (s, 1H). (m/z)=229 (M+H)+.

Provenance & Evidence