Cs2CO3 (15.5 g, 47.5 mmol) was added to (24.1) (3 g, 14.4 mmol) and 3-methoxy-4-hydroxyphenylacetic acid (2.63 g, 14.4 mmol) in DMSO (30 mL) at room temperature. The mixture was then stirred at 80° C. for 4 h. After cooling, the reaction mixture was treated with water (50 mL), 3N HCl (35 mL) and EtOAc (100 mL). The product was insoluble in EtOAc, but stayed in the organic layer. So the organic layer was washed with water 4 times to get rid of all the salts, and the organic layer was separated, concentrated and dried under vacuum to afford 24.2. MS ESI (pos.) m/z: 355.1 (M+H). 1H NMR (DMSO-d6) δ 8.99 (dd, 1H); 8.24 (m, 2H); 7.77 (dd, 1H); 7.29 (d, 1H); 7.21 (d, 1H); 7.18 (d, 1H); 6.96 (dd, 1H); 3.73 (s, 3H); 3.65 (s, 2H).
