A solution of 2,5,9-trimethyl-11-(2,6,6-trimethyl-1-cyclohexen-1-yl)-2,4,6,8,10-undecapentaene-1-ol (1.6 g, 5 mmol) and pyridine (9.6 ml, 7.3 mmol) in 15 ml of anhydrous methylene chloride is stirred in an ice bath and a solution of acetyl chloride (0.37 ml, 5.25 mmol) in 5 ml of anhydrous methylene chloride is added dropwise. The mixture is stirred at 0° C. for 11/2 hours and at room temperature for 30 minutes and then taken up in 250 ml of ether. The solution is washed with ice cold 5% aqueous sodium bicarbonate and water, dried (MgSO4) and evaporated to give the crude product; recrystallization from ethanol affords the titled compound.
