1,1-Ethylenedioxy-4-(2,2-dibromovinyl)cyclohexane → 8-Ethynyl-1,4-dioxaspiro[4.5]decane

Participants

Reaction Conditions

Reaction Steps

A solution of 14 g of 1,1-ethylenedioxy-4-(2,2-dibromovinyl)cyclohexane in 70 ml of tetrahydrofuran was cooled to -20° C. and treated slowly at this temperature with 76.62 ml of a 1.4M solution of butyl lithium in hexane (exothermic reaction). The cooling bath was removed and the mixture was left to warm to 20° C. within about 20 minutes. The mixture was subsequently treated with 150 ml of water and extracted three times with diethyl ether. The organic phases were washed twice with water and the wash-water was back-extracted with diethyl ether. The organic phases were dried over magnesium sulphate, filtered and evaporated. Low-pressure chromatography of the resulting, yellow liquid (8 g) on silica gel with ethyl acetate/petroleum ether (vol. 7:93) gave 6.5 g (91%) of 4-ethynyl-1,1-ethylenedioxycyclohexane as a clear liquid.

Provenance & Evidence