21243-09-4 → 8-fluoro-2,3-dihydro-4H-thiochromen-4-one

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Reaction Conditions

Reaction Steps

3-[(2-Fluorophenyl)sulfanyl]propanoic acid (4.0 g, 20 mmol) was mixed with concentrated sulphuric acid (20 ml) at 0–5° C. The reaction solution was stirred at 0 to 5° C. for 3 h then allowed to warm up to room temperature overnight. The mixture was quenched dropwise into ice to give a white suspension. The aqueous phase was extracted with ethyl acetate (1×200 ml, 1×100 ml). The combined organic phases were washed with saturated sodium bicarbonate solution (1×50 ml), water (1×50 ml), 1M hydrochloric acid (50 ml) and water (2×50 ml). The organic phase was dried over magnesium sulphate, filtered and concentrated under vacuum. The title compound was isolated as a yellow solid (2.10 g, 11.5 mmol, 58%).

Provenance & Evidence