Phosphorus oxychloride → 8-(Piperazin-1-yl)-5-(thiophen-2-yl)imidazo[1,5-a]pyrazine

Participants

Reaction Conditions

Reaction Steps

A 50 mL round bottom flask was charged with tert-butyl 4-(3-(formamidomethyl)-5-(thiophen-2-yl)pyrazin-2-yl)piperazine-1-carboxylate (0.40 g, 1.0 mmol) and toluene (20 mL). To the above mixture was added dropwise POCl3 (0.76 g, 5.0 mmol). The resulting mixture was heated at 90° C. for 1 h. Work-up: the reaction mixture was poured into saturated aqueous NaHCO3 and extracted with dichloromethane. The combined organic layers were washed with brine, dried over anhydrous Na2SO4 and concentrated in vacuo. The residue was further purified by flash column chromatography on silica gel with 5% MeOH in dichloromethane, to afford 0.25 g (85%) of the product. 1H NMR (300 MHz, CDCl3) δ: 8.41 (s, 1H), 7.74 (s, 1H), 7.46 (dd, J=5.1, 1.2 Hz, 1H), 7.37 (dd, J=3.6, 1.2 Hz, 1H), 7.25 (s, 1H), 7.19 (dd, J=5.1, 3.6 Hz, 1H), 3.89 (t, J=5.1 Hz, 4H), 3.08 (t, J=5.1 Hz, 4H). MS m/z: 286 (M+H+).

Provenance & Evidence