*(1E,6E)-1,7-bis(4-Hydroxy-3-methoxyphenyl)-4,4-dimethylhepta-1,6-diene-3,5-dione* (**2m**)

To a stirred solution of compound **2** (0.450 g, 0.72 mmol) in CH3OH (6 mL) were added NaOMe (0.116 g, 2.16 mmol) at room temperature. The reaction mixture was stirred at the same temperature for 2 h and then H2O (5 mL) and diluted HCl(aq) (1 *N*, 1 mL) were added to quench the reaction. The aqueous layer was separated and extracted with CH2Cl2 (3 × 6 mL). The combined organic extracts were washed with brine, dried over MgSO4, filtered and concentrated to give the crude product, which was then purified by flash chromatography on silica gel with EtOAc/*n*-hexane/CH2Cl2 (1:2:1) to afford **2m** (0.245 g, 86% yield) as an orange solid; mp <sup>=</sup> <sup>104</sup>−<sup>106</sup> ◦C; 1H-NMR (CDCl3) <sup>δ</sup> 7.69 (d, *<sup>J</sup>* <sup>=</sup> 15.5 Hz, 2H), 7.12 (dd, *J* = 8.0, 1.5 Hz, 2H), 7.01 (s, 2H), 6.91 (d, *J* = 8.5 Hz, 2H), 6.65 (d, *J* = 15.5 Hz, 2H), 5.97 (s, 2H), 3.94 (s, 6H), 1.48 (s, 6H); 13C-NMR (CDCl3) δ 198.2, 148.6, 146.8, 144.5, 126.8, 124.1, 119.1, 114.8, 109.8, 60.8, 56.0, 14.1; HRMS [ESI]<sup>+</sup> calculated for C23H24NaO6: 419.1471 [M + Na]+; found: 419.1480
