Water → 3,3-Diethyl-1,5-dioxaspiro[5.5]undecan-9-one

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Reaction Steps

30 g (0.27 mmol) of cyclohexane-1,4-dione, 35.4 g (0.27 mol) of 2,2-diethylpropane-1,3-diol and 360 mg of para-toluenesulfonic acid were heated in 200 ml of toluene on a water separator. After the mixture had been cooled to room temperature and the water of reaction separated off, the organic phase was washed with a semisaturated sodium hydrogen carbonate solution and dried over magnesium sulfate. After the solvent had been evaporated, 65 g of crude product were obtained which was purified by flash chromatography (ethyl acetate/petroleum ether=1:4). The first fraction contained the 1,4-diketal which was formed as secondary product (10 g). The main fraction contained 28.5 g (47%) of a yellow oil.

Provenance & Evidence