Methyl iodide → 1-benzenesulfonyl-2-methyl-4-trifluoromethyl-1H-indole

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Reaction Steps

3 ml of n-butyllithium (1.6M in hexane) are added dropwise to a solution of 0.7 ml of diisopropylamine in 10 ml of tetrahydrofuran under argon at −30° C. The solution is stirred for 30 min at ambient temperature, and cooled to −60° C. and a solution of 1.07 g of 1-benzenesulfonyl-4-trifluoromethyl-1H-indole in 10 ml of tetrahydrofuran is added dropwise. The reaction medium is brought back up to ambient temperature and then taken back to −60° C. in order to add, dropwise, 0.31 ml of methyl iodide. After addition, the mixture is allowed to come back up to 0° C. with stirring for 10 minutes, and then to 10° C. for 10 min, before adding a further 0.3 ml of methyl iodide. After returning to ambient temperature, the reaction mixture is stirred for 1 h 30 and then poured into a 10% ammonium chloride solution and extracted with ethyl acetate. The organic phases are washed with a saturated sodium chloride solution, dried over magnesium sulfate, filtered, and concentrated under reduced pressure. The residue is purified by silica column chromatography, elution being carried out with a mixture of heptane and diisopropyl ether (98/2, then 95/5: v/v), so as to give 476 mg of 1-benzenesulfonyl-2-methyl-4-trifluoromethyl-1H-indole, in the form of an oil, which is used in the next step.

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