Sodium hydride (60% dispersion in mineral oil, 0.19 g, 4.75 mmol) was suspended in DMSO (2.5 mL) and ethyl mercaptoacetate (0.28 mL, 2.54 mmol) was added portionwise using a water bath to moderate the exotherm. On complete addition, the water bath was removed and stirring continued for 15 minutes. A solution of di-tert-butyl (3-fluoro-4-formylphenyl)(methyl)malonate (0.81 g, 2.30 mmol) in DMSO (0.5 L) was added in one portion. The orange solution was warmed with a heat gun to give a dark brown solution. H2O was added (150 mL) and the products were extracted into EtOAc (2×100 mL). The combined organic extracts were washed with brine, dried over MgSO4 and concentrated in vacuo. Purification of the residue by MPLC gave the desired product (pale yellow solid). 1H NMR (CDCl3) δ 8.01 (s, 1H), 7.88 (d, J=1.8 Hz, 1H), 7.81 (d, J=8.4 Hz, 1H), 7.48 (dd, J=8.4, 1.8 Hz, 1H), 4.39 (q, J=7.2 Hz, 2H), 1.84 (s, 3H), 1.47 (s, 18H), 1.40 (t, J=7.2 Hz, 3H).
