Diisopropylamine → (E,E)-5,9,13-Trimethyl-4,8,12-tetradecatrienoic acid, 1,1-dimethylethyl ester

Participants

Reaction Conditions

Reaction Steps

To a solution of 9.60 ml (68.5 mmol, 1.5 eq.) of diisopropylamine in 100 ml of THF at -78° C. under argon was added 28.2 ml (45.0 mmol, 1.0 eq.) of 1.6M n-butyllithium in hexanes over 20 minutes. After warming to 0° C. for 15 minutes, the solution was recooled to -78° C. and 6.05 ml (45 mmol, 1.0 eq) of t-butyl acetate was added over 20 minutes. After an additional 15 minutes, 16.0 ml (92 mmol, 2.05 eq.) of hexamethylphosphoramide (HMPA) was added, followed by a solution of 12.53 g (45.0 mmol) of Part A(1) farnesyl bromide in 100 ml of THF over 20 minutes. The reaction was stirred at -78° C. for 2.5 hours, quenched with saturated NH4Cl and allowed to warm to room temperature. After diluting with 400 ml of ethyl acetate, the mixture was washed with four 100 ml portions of water, and 200 ml of brine, dried over MgSO4 and evaporated to provide 12.96 g of crude product as a yellow oil. Purification by flash chromatography on 1 kg of silica gel, eluted with 1:9 ethyl acetate:petroleum ether afforded 9.39 g (65%) of title compound as a pale yellow oil.

Provenance & Evidence