Acetonitrile → 5,5-dimethyl-3-oxohexanenitrile

In a 500 mL dried round-bottom flask, acetonitrile (6.31, 153.6 mmol) dissolved in THF (50 mL) was treated with LiHMDS (156.3 mL, 1.0 M solution in THF) at −78° C. To this solution was added methyl 3,3-dimethylbutanoate in THF (50 mL) at −78° C. The solution was warmed to rt, and NaHCO3 (100 mL, saturated solution) was added. The layers were separated and the aqueous layer was extracted with ether (3×100 mL). The combined organic layers were washed with brine, dried over Na2SO4, filtered, and concentrated under reduced pressure to give the desired product, which was used in the next step without purification. 1H NMR (300 MHz, CD2Cl2) δ 3.47 (s, 2H), 2.44 (s, 2H), 1.03 (s, 9H).