Ammonia → 2,2-Dimethyl-6-trifluoromethylthio-2H-1-benzopyran

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Reaction Steps

1.45 g of 6-mercapto-2,2-dimethyl-2H-1-benzopyran (prepared as described in Preparation 6) was suspended in 30 ml of liquid ammonia, and 8.23 g of trifluoromethyl iodide were then added to the suspension at -60° C. in an atmosphere of nitrogen. The resulting mixture was then irradiated at -65° C. for 2 hours and then at 25° C. for 2 hours, using a low pressure mercury lamp. At the end of this time, the reaction mixture was diluted with ethyl acetate and washed with dilute aqueous hydrochloric acid, with water, with an aqueous solution of sodium hydrogencarbonate and with a saturated aqueous solution of sodium chloride, in that order. The organic layer was then dried over anhydrous sodium sulfate and concentrated by distillation under reduced pressure. The resulting residue was purified by column chromatography through silica gel, using a 20:2:1 by volume mixture of cyclohexane, chloroform and ethyl acetate as the eluent, to afford 1.17 g of the title compound as an oil.

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