反应详情

To a solution of 40.2 g (0.295 mole) of the title compound of Example 1 in 800 ml of a 8:1 dioxane/water mixture was added 4 g (0.21 mole) of p-toluenesulfonic acid. The reaction mixture was heated at 83° for 36 hours under argon, cooled, and diluted with 500 ml of ethyl acetate. The organic phase was washed once with water and two times each with 5% sodium bicarbonate solution and brine solution. The aqueous washes were combined and extracted with ethyl acetate. The combined organic phases were dried over sodium sulfate, filtered, and concentrated. Chromatography of the combined crude materials on silica gel (using 25% ethyl acetate in hexane as eluent) gave 12.45 g of the intermediate compound 4-hydroxy-5-(2-propynyl)-2-cyclopenten-1-one as a viscous oil. Structure assignment was confirmed by the proton nmr spectrum.