Sodium Iodide → 4,7-dimethyl-6,7,8,9-tetrahydro-5H-benzocyclohepten-5-one

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Reaction Steps

A mixture of the 7-methyl-6,7,8,9-tetrahydro-5H-benzocyclohepten-5-one (6.63 g, 38.1 mmol) synthesized in Reference Example 10, (d), trimethylsilane chloride (7.25 ml, 57.1 mmol), sodium iodide (8.56 g, 57.1 mmol), triethylamine (7.95 ml, 57.0 mmol) and acetonitrile (80 ml) was stirred at room temperature for 4 hours. Then, the solvent was distilled off under reduced pressure and the resulting residue was extracted with a mixed solvent of n-hexane/diethyl ether (1/1). The extract solution was concentrated under reduced pressure and the resulting residue was dissolved in n-hexane (150 ml), followed by adding thereto tetramethylethylenediamine (13.5 ml, 89.4 mmol), and the reaction mixture was cooled to 0° C. Then, n-butyllithium (a 3.0 M n-hexane solution; 30 ml, 90.6 mmol) was added dropwise to the reaction mixture and the resulting mixture was stirred at room temperature for 20 minutes and then at 60° C. for 2.5 hours. The reaction mixture was cooled to room temperature and methyl iodide (3.55 ml, 57.0 mmol) was added thereto, followed by stirring at room temperature for 30 minutes. The reaction mixture was diluted with n-hexane and the dilution was washed with water and dried over anhydrous magnesium sulfate. The solvent was distilled off under reduced pressure and the resulting residue was purified by a silica gel column chromatography to obtain 3.43 g of 4,7-dimethyl-6,7,8,9-tetrahydro-5H-benzocyclohepten-5-one.

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