Hydrogen Peroxide → t-Butyl 3-(1-carboxycyclopentyl)propanoate

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Reaction Steps

To a solution of 2-acetyl-2-[2-(tert-butoxycarbonyl)ethyl]-cyclohexanone (see Preparations 1 and 2) (2.0 g, 7.45 mmol) and concentrated sulphuric acid (98% w/w, one drop) in toluene (6.0 ml) was added, dropwise, a 30% aqueous solution of hydrogen peroxide (1.05 ml, 9.31 mmol) at room temperature. The mixture was stirred for 68 hours at room temperature, treated with a further quantity of a 30% aqueous solution of hydrogen peroxide (0.4 ml, 3.72 mmol) and stirred for a further 16 hours at room temperature. The mixture was partitioned between toluene (25 ml) and 5% aqueous sodium sulphite solution and the layers separated. The toluene layer was washed with dilute aqueous ammonia solution (25 ml of 0.880 ammonia in 200 ml of distilled water, 4×25 ml). The combined aqueous extracts were washed with toluene (25 ml), acidified to pH 2-3 with 5.0N aqueous hydrochloric acid solution and extracted with toluene (3×25 ml). The combined toluene extracts were dried over magnesium sulphate, filtered and concentrated under reduced pressure to give an oil, (1.11 g, 61%). The crude product was crystallized from pentane (7.5 ml/g) to give the title compound as a colorless solid. Rf. 0.28 (silica, hexane/ethyl acetate 2:1).

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