Hydrochloric Acid → N-(3-Fluorophenyl)-2-oxo-2,3-dihydro-3-benzo[b]thiophenecarboxamide

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Reaction Steps

A solution of 6 g of 2,3-dihydro-2-oxo-benzo[b]thiophene in 40 ml of tetrahydrofurane is added dropwise, at 10° to 20°, to a stirred suspension of 1.93 g of a 50% strength sodium hydride/mineral oil suspension in 50 ml of tetrahydrofurane. The mixture is stirred for a further 30 minutes at room temperature and 5.5 g of 3-fluoro-phenyl isocyanate are then added slowly dropwise, an exothermic reaction taking place. The reaction mixture is then stirred for a further one hour at room temperature and for one hour at 40° and is poured into a mixture of 500 ml of ice water and 50 ml of 2 N hydrochloric acid and the precipitate, which at first is oily but immediately crystallises, is filtered off and recrystallised from acetone/petroleum ether. N-(3-Fluorophenyl)-2-oxo-2,3-dihydro-3-benzo[b]thiophenecarboxamide with a melting point of 169°-171° is obtained.

Provenance & Evidence