3.1.6. *(1E,6E)-1,7-bis(3,4-Dimethoxyphenyl)-4,4-bis(hydroxymethyl)hepta-1,6-diene-3,5-dione* (**12**)

To a stirred solution of DMC (1.270 g, 3.20 mmol) in THF (20 mL, containing 0.6 M formaldehyde) was added DBU (15 mg, 0.10 mmol). The reaction mixture was stirred at 0 ◦C for 30 min. The reaction mixture was concentrated under vacuum and then purified by flash chromatography on silica gel with MeOH/CH2Cl2 (1:32) to afford **12** (558 mg, 42% yield) as a yellow solid; mp = 174–176 ◦C; 1H-NMR (DMSO-d6) δ 7.49 (d, *J* = 15.5 Hz, 2H), 7.48 (d, *J* = 2.0 Hz, 2H), 7.24 (d, *J* = 8.5 Hz, 2H), 6.97–6.91 (m, 4H), 4.78 (t, *J* = 4.5 Hz, 2H), 4.19 (d, *J* = 4.5 Hz, 4H), 3.79 (s, 12H); 13C-NMR (DMSO-d6) δ 196.2, 151.7, 149.1, 142.8, 127.4, 123.8, 120,9, 112.1, 111.3, 71.6, 60.1, 56.1, 56.0; HRMS [ESI]<sup>+</sup> calculated for C25H28NaO8: 479.1682 [M + Na]+; found: 479.1677.
