Sodium Hydroxide → 6-chloro-2-(2-chlorophenyl)-1,7-naphthyridin-4(1H)-one

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Reaction Conditions

Reaction Steps

5-(tert-Butoxycarbonylamino)-2-chloroisonicotinic acid (502 mg, 1.84 mmol) was suspended in polyphosphoric acid (9.5 g, 102 mmol) at ambient temperature and stirred for 10 mins causing a bright yellow coloration and visible evolution of gas. 2′-Chloroacetophenone (570 mg, 3.69 mmol) was added and the mixture heated to 150° C. for 2.5 h. The mixture was diluted with cold water (50 mL), and then cooled in ice and treated with solid sodium hydroxide (6.0 g, 150 mmol) to pH ˜7. The mixture was filtered and the recovered oily solids washed with water, dissolved in methanol and reconcentrated in vacuo. The residue was purified by flash chromatography (silica, ISCO, 0.5-20% methanol in DCM) to afford the title compound as a cream solid (29.2 mg, 5.5%). 1H NMR (400 MHz, MeOD) δ 8.87 (s, 1H), 8.12 (s, 1H), 7.64-7.58 (m, 2H), 7.58-7.46 (m, 2H), 6.47 (s, 1H); NH absent. LCMS: M+H+=291 & 293.

Provenance & Evidence