Ethyl cyanoacetate → 2-Cyano-hex-5-enoic acid ethyl ester

To a flame dried flask charged with NaH (1.4 g, 35.46 mmol, 60% dispersion in mineral oil) and DMF (90 mL) equipped with a Firestone valve and under a stream of dry nitrogen was added, dropwise ethylcyanoacetate (3.14 mL, 29.56 mmol) over 20 min. The reaction mixture was then allowed to stir for 30 min, followed by addition of 4-bromobutene (3.0 mL, 29.56 mmol). The reaction mixture was allowed to stir overnight after which the solvent was removed by reduced pressure. The resulting crude mixture was dissolved in ethyl acetate, washed 3 times with 1N HCl solution and once with a saturated solution of brine. The organic and aqueous layers were separated and the organic layer was dried with sodium sulfate, filtered and the solvent was removed under reduced pressure to yield a residue. The residue was purified by flash chromatography using a mixture of 9:1 heptanes to ethyl acetate to yield a clear colorless oil.