反应详情

温度

0 °C

8.15 g of potassium tert.-butylate were added to a solution of 38 g of triphenyl 2,2-ethylenedioxy-pentyl phosphonium bromide in 400 ml of dimethylformamide cooled to 0° C. and then 12.75 g of 6-methoxy-6-methyl-2-heptanone were added. The mixture was stirred for 4 hours at 0° C. and was then poured into water. The mixture was extracted with petroleum ether (b.p.= 40°-75° C.) and the extracts were washed with water, dried over sodium sulfate and evaporated to dryness. The yellow oil was chromatographed over silica and was eluted with a 8-2 benzene-ethyl acetate mixture to obtain 9.15 g of 2,2-ethylenedioxy-10-methoxy-6,10-dimethyl-5-undecene in the form of a colorless oil which was a mixture of the E and Z isomers with respect to the double bond in the 5-position. A supplementary chromatography under pressure and elution with a 9-1 benzene-ethyl acetate mixture gave a separation of the E and Z isomers.

1. extractionThe mixture was extracted with petroleum ether (b.p.= 40°-75° C.)
2. washthe extracts were washed with water
3. dry with materialdried over sodium sulfate
4. customevaporated to dryness
5. customThe yellow oil was chromatographed over silica
6. washwas eluted with a 8-2 benzene-ethyl acetate mixture