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14 g of sodium hydride in a 50% suspension in oil were added to a solution of 28 g of 4-methyl-3-pentenol [Julia et al, Bull. Soc. Chim., (1960), p. 1072] in 250 ml of dimethylformamide and after stirring the mixture for 1 hour, 66 g of 5-bromo-2,2-ethylenedioxy-pentane were added thereto while keeping the temperature below 35° C. The mixture was stirred at room temperature for 17 hours and the reaction mixture was then poured into water. The mixture was extracted with petroleum ether (b.p.= 40°-75° C.) and the organic phase was washed with water, dried over sodium sulfate and evaporated to dryness. The residue was rectified to obtain 20 g of 2,2-ethylenedioxy-10-methyl-6-oxa-9-undecene in the form of a colorless liquid with a boiling point of 75° C. at 0.05 mm Hg.

1. customthe temperature below 35° C
2. stirringThe mixture was stirred at room temperature for 17 hours
3. extractionThe mixture was extracted with petroleum ether (b.p.= 40°-75° C.)
4. washthe organic phase was washed with water
5. dry with materialdried over sodium sulfate
6. customevaporated to dryness