Ethyl 2-chloroacetoacetate → 6-But-3-ynyl-3-chloro-6-cyclopentyl-dihydro-pyran-2,4-dione

関与物質

反応条件

反応手順

To a slurry of sodium hydride (480 mg, 60% suspension in mineral oil, 12 mmol) in THF (30 mL) cooled to −10° C. was added ethyl-2-chloroacetoacetate (1.66 mL, 12 mmol). The reaction was stirred until all gas evolution ceased. The reaction was then cooled to −40 ° C. and a solution of butyl lithium (4.8 mL, 2.5 M in ether, 12 mmol) was added. The reaction was stirred for 10 minutes, and then 1-cyclopentyl-pent-4-yn-1-one (0.60 g, 4 mmol) was added as a solution in THF (10 mL). The reaction was stirred for 1 hour, and then quenched with 40 mL saturated ammonium chloride. The solution was acidified further with 5 mL of 6 N HCl. The layers were separated, and the aqueous was extracted with ethyl acetate. The organics were combined and washed with water and then saturated sodium chloride. The organic phase was dried over sodium sulfate, filtered, and then concentrated. The crude product was then dissolved in toluene (13 mL) and bis(dibutylchlorotin) (1.027 g) was added. The solution was heated to reflux for one hour. The reaction was then concentrated and chromatographed (40 g silica gel, 2% MeOH in CH2Cl2) to yield the title compound (0.820 g, 76%).

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