5-Benzyloxy-2-hydroxy-benzaldehyde (Kappe, T.; Witoszynskyj, T. Arch. Pharm., 1975, 308 (5), 339-346) (169 g, 741 mmol), ethyl bromoisobutyrate (164 mL, 1.11 mol), and cesium carbonate (240 g, 741 mmol) in dry DMF (600 mL) were heated at 80° C. for 15 h. Additional cesium carbonate (5 g) and ethyl bromoisobutyrate (20 mL) were added, and the reaction mixture was heated for 6 h. The reaction mixture was cooled, diluted with EtOAc (4 L), and washed with water (3×2 L). The organic layer was dried (Na2SO4) and concentrated to a brown oil. The crude product was recrystallized from EtOAc (150 mL) with hexanes until turbid to give the title compound as a pale yellow solid (210 g, 83%): mp 65° C.; 1H NMR (400 MHz, CDCl3) δ 1.24 (t, 3H, J=7.1 Hz), 1.62 (s, 6H), 4.23 (q, 2H, J=7.1 Hz), 6.81 (d, 1H, J=8.8 Hz), 7.10 (dd, 1H, J=4.6, 9.0 Hz), 7.30-7.43 (m, 6H); MS (ES) m/e 343.1 [M+1].
