Hexane → 4-bromo-9a-butyl-3-methylene-2,3,9,9a-tetrahydro-1H-fluoren-7-ol

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反応条件

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A suspension of methyltriphenylphosphonium bromide (373 mg, 1.04 mmol) in anhydrous tetrahydrofuran (2 mL) was cooled in an ice bath and stirred under a nitrogen atmosphere while 2.5 N nBuLi in hexane (0.36 mL, 0.90 mmol) was added by syringe. The mixture was stirred at 0° C. for 10 minutes to complete formation of the methylenetriphenylphosporane reagent. A solution of 4-bromo-9a-butyl-7-hydroxy-1,2,9,9a-tetrahydro-fluoren-3-one (50 mg, 0.15 mmol) in tetrahydrofuran (1 mL) was added to the reaction mixture and the ice bath was removed. The resulting mixture was stirred at room temperature for 3.2 hours, then at 50° C. for 1.5 hour, and finally at room temperature for an additional 17 hours. The mixture was partitioned between saturated aqueous NH4Cl (5 mL) and EtOAc (9 mL). The organic phase was acidified with 2N HCl (0.2 mL), washed with brine (4 mL), dried over MgSO4, filtered, and evaporated under vacuum to an oil (90. mg). The crude product was purified by preparative layer chromatography on a 0.1×20×20 cm silica gel GF plate using 3:1 hexanes-EtOAc as developing solvent. The UV visible band at Rf 0.50-0.63 was eluted with EtOAc. The eluant was concentrated under vacuum to a residue which was lyophilized from benzene to afford 4-bromo-9a-butyl-3-methylene-2,3,9,9a-tetrahydro-1H-fluoren-7-ol.

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