Acetic Anhydride → 1-[6-(4-Fluorophenyl)imidazo[2,1-b][1,3]oxazol-5-yl]ethanone

Participants

Reaction Steps

A solution of 6-(4-fluorophenyl)-imidazo[2,1-b]oxazole (2.5 g, 0.0124 mol) in acetic anhydride (60 ml) was heated to 140° C. and then treated with concentrated sulfuric acid (5 drops). After 15 minute at that temperature, HPLC showed clean conversion and the reaction mixture was quenched by the addition of ice cold water (150 ml). The mixture was extracted with ethyl acetate (3×150 ml). The combined extracts were washed with a saturated aqueous sodium chloride solution (300 ml), dried over magnesium sulfate and concentrated in vacuo as a brown solid. Trituration from a mixture of hexanes/ethyl acetate (1:1) provided 2.2 g (72.6%) of a pale yellow solid. M.p.=173° C.; 300 MHz 1H NMR (DMSO-d6) δ 8.25-8.19 (m, 2H), 7.75-7.68 (m, 2H), 7.35-7.25 (m, 2H), 2.15 (s, 3H). LCMS: 245 [M+H].

Provenance & Evidence