Synthesis of (1-Ethenyl)heptanyl 3-Ketobutanoate from 3-Hydroxy-1-nonene -- DMAP as Catalyst

S.R. Wilson and C.E. Augelli, Org. Synth. 68, 210 (1990)

1. A solution of 3-hydroxy-1-nonene (7.5 g, 0.053 mol) in anhydrous ether (250 mL) is stirred under a nitrogen a®osphere.  To this solution, diketene (5.04 g, 0.060 mol) is added using a syringe followed by DMAP (0.591 g, 0.0049 mol).
2. The reaction mixture slightly exotherms and stirring is continued for a further 15 min. 
3. The reaction mixture is quenched by the addition of 0.1% sodium hydroxide solution (100 mL) followed by ether (100 mL).  The layers are separated and the organic layer washed with 0.1% sodium hydroxide solution (50 mL) followed by brine.  The organic phase is dried over magnesium sulfate and concentrated under reduced pressure to afford 1-ethenyl)heptanyl 3-ketobutanoate (11.3 g, 94%) as a pale yellow oil.  Further purification can be accomplished by distillation (b.p. 113-114°C at 1.4 mm) to afford a colorless oil.