Sodium hydride → HCID 68557054, compound

A suspension of 60% dispersion sodium hydride (65.1 mg, 1.627 mmol) in anhydrous THF (2.5 mL) was treated with a solution of trimethyl phosphonoacetate (235 μL, 1.627 mmol) in THF (1 mL) over 5 min. The mixture was stirred at RT for 30 min and then treated with a solution of 1-(4-chloro-3-methoxyphenyl)piperidin-4-one (300 mg, 1.252 mmol) in THF (3 mL). The reaction was stirred at RT for 1 h before it was partitioned between saturated NH4Cl and EtOAc. The extract was dried (Na2SO4) and concentrated to give the crude product, which was purified by flash chromatography (12 g silica gel cartridge and gradient elution from 0 to 30% EtOAc/hexanes) to afford methyl 2-(1-(4-chloro-3-methoxyphenyl)piperidin-4-ylidene)acetate (288 mg, 0.974 mmol, 78% yield) as a white solid. 1H-NMR (400 MHz, CDCl3) δ ppm 7.19 (1 H, d, J=8.79 Hz), 6.49 (1 H, d, J=2.42 Hz), 6.44 (1 H, dd, J=8.79, 2.64 Hz), 5.73 (1 H, s), 3.88 (3 H, s), 3.70 (3 H, s), 3.26-3.34 (4 H, m, J=5.82, 5.49, 5.33, 5.33 Hz), 3.10 (2 H, t, J=5.38 Hz), 2.45 (2 H, t, J=5.27 Hz).