(Z)-(3-nonenyl)-triphenylphosphonium iodide → (Z,Z)-2-[(2,2-dimethyl-3,6-dodecadienyl)oxy]-tetrahydro-2H-pyran

Beteiligte Stoffe

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Reaktionsschritte

A 2.7 ml portion of n-butyllithium (1.6 M in hexane) was slowly added at -76° C., under argon to a solution of 2.7 g (5.24 mmoles) of (Z)-(3-nonenyl)-triphenylphosphonium iodide in a mixture of 7.5 ml of 2:1 tetrahydrofuran-hexamethylphosphorictriamide by syringe. The solution turned orange-red in color. Without delay, a solution of 0.700 g (3.76 mmoles) of 2,2-dimethyl-3-[(tetrahydro-2H-pyran-2-yl)oxy]-propanal in 1 ml of tetrahydrofuran was added dropwise to the solution. The resulting mixture was stirred at -78° C. for 30 minutes. The temperature was then allowed to rise to 0° C. After 1 hour, the reaction mixture was poured into brine, and the product extracted twice with 1:1 hexane-ether. The organic layer was dried using MgSO4, and the solvents evaporated in vacuo. Purification of the crude product by rapid chromatography on a silica-gel column gave 1.0 g (90.2%) of (Z,Z)-2-[(2,2-dimethyl-3,6-dodecadienyl)oxy]-tetrahydro- 2H-pyran. This material was dissolved in 10 ml of methanol and treated with 0.1 ml of 2 N hydrochloric acid. After stirring for 2 hours at room temperature, the volume of methanol was reduced to about 3 ml by concentration under reduced pressure. The remaining solution was diluted with ether, and the ether solution washed with saturated sodium bicarbonate solution and brine and thereafter dried using MgSO4 and then concentrated under reduced pressure. The residue (0.780 g) was chromatographed on a silica gel column. Hexane-ether (4:1) eluted 0.690 g (79.1%) of pure (Z,Z)-2,2-dimethyl-3,6-dodecadien-1-ol. (98.6% pure by GC-analysis).

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