Water → tert-butyl 2-methyl-8-(1-methylethenyl)-2,3-dihydrothieno[2,3-f][1,4]oxazepine-4(5H)-carboxylate

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Reaction Steps

A mixed solution of tert-butyl 8-bromo-2-methyl-2,3-dihydrothieno[2,3-f][1,4]oxazepine-4(5H)-carboxylate (418 mg) obtained in Example 6, steps 1-6, isopropenylboronic acid pinacol ester (0.293 ml), dichlorobis(triphenylphosphine)palladium (42 mg) and potassium carbonate (498 mg) in DME-water (1:1, 10 mL) was stirred at 85° C. for 1 hr under a nitrogen stream. The reaction solution was cooled to room temperature, water was added, and the mixture was extracted with ethyl acetate. The extract was washed with water and saturated brine, and dried over magnesium sulfate, and the solvent was evaporated under reduced pressure. The residue was purified by silica gel column chromatography (solvent gradient; 5→12% ethyl acetate/hexane) to give the title compound (274 mg, 74%) as a colorless oil.

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