Tetrahydrofuran → (5Z)-3-methylnon-5-enyl acetate

Under an atmosphere of nitrogen, a solution of 46.3 g (413 mmol) of potassium tert-butoxide in 250 mL of dry THF was a added between −15° C. and −10° C. to a stirred mixture of 150 g (376 mmol) butyl triphenylphosphonium bromide in 500 mL of dry THF. After complete addition, stirring was continued at −10° C. for 30 min, prior to the dropwise addition of 65.3 g (413 mmol) of 3-methyl-5-oxopentyl acetate in 250 mL of dry THF within a period of 30 min. Stirring was continued a further 15 min at −10° C., before the cooling bath was removed and the reaction mixture was allowed to warm to room temp. After 3 h of stirring at room temp., the reaction mixture was poured into 1 L of water, the organic layer separated and aqueous one extracted twice with 1 L of ether each. The combined organic extracts were washed with water and brine, dried with sodium sulphate, and concentrated under reduced pressure. The crude material (191 g) was purified by flash chromatography (1.00 kg of silica gel, pentane/ether, 19:1, Rf=0.40) to afford 57.9 g (78%) of (5Z)-3-methylnon-5-enyl acetate as a colourless liquid.