To a solution of 3-(4-fluoro-3-(methylsulfonyl)phenyl)-4-hydroxybenzaldehyde (28) (315 mg, 1.1 mmol, 1 eq.) in DMF (10 mL) was added Cs2CO3 (715 mg, 2.2 mmol, 2 eq.) and t-butyl 2-bromoacetate (236 mg, −1.2 mmol, 1.2 eq.). After stirring at room temperature, for 16 h, the solvent was removed in vacuo, and the resultant residue was extracted between EtOAc and H2O (3×20 mL). The organic layer was dried (Na2SO4), and concentrated in vacuo. The resultant residue was purified by column chromatography (eluent: PE:EA=1:1) to give 250 mg (57%) of t-butyl 2-(2-(4-fluoro-3-(methylsulfonyl)phenyl)-4-formylphenoxy)acetate (29) as oil.
