Cesium carbonate → 2-Cyclopropyl-4H-thieno[2,3-c]pyrrol-6(5H)-one

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Reaction Conditions

Reaction Steps

A 100-mL single-neck round-bottomed flask equipped with a reflux condenser, magnetic stirrer and nitrogen inlet was charged with 116f (900 mg, 4.12 mmol), potassium cyclopropyltrifluoroborate (733 mg, 4.95 mmol), cesium carbonate (4.03 g, 12.4 mmol), toluene (18 mL), water (1 mL). After bubbling nitrogen through the resulting suspension for 30 min, palladium(II) acetate (279 mg, 0.412 mmol) and n-butyldi-1-adamantylphosphine (222 mg, 0.618 mmol) were added, and the reaction mixture was heated at 100° C. for 14 h. After this time, the mixture was cooled to room temperature and diluted with ethyl acetate (150 mL) and water (30 mL). The organic layer was separated, and the aqueous layer was extracted with ethyl acetate (3×150 mL). The combined organic layers were dried over sodium sulfate and concentrated under reduced pressure. The residue was purified by column chromatography (silica, 0% to 5% methanol/methylene chloride) to afford a 35% yield (254 mg) of 116g as an off-white solid: mp 109-110° C.; 1H NMR (300 MHz, CDCl3) δ 6.72 (s, 1H), 6.08 (br s, 1H), 4.28 (s, 2H), 2.16 (m, 1H), 1.09 (m, 2H), 0.84 (m, 1H); MS (ESI+) m/z 180.1 (M+H).

Provenance & Evidence