3.1.10. *(E)-1,7-bis(4-Hydroxy-3-methoxyphenyl)-4,4-dimethylhept-1-ene-3,5-dione* (**18**)

To a stirred solution of compound **2m** (0.740 g, 1.87 mmol) in EtOAc (10 mL) was added Pd/C (37 mg, 5% *w*/*w*) in one portion. The resulting mixture was hydrogenated under 1 atmosphere of H2 at room temperature. After 1 h, the mixture was filtered by celite and concentrated to give the crude product, which was purified by flash chromatography on silica gel with EtOAc/*n*-hexane/CH2Cl2 (1:2:1) to afford compound **18** (140 mg, 19% yield) as a light-yellow oil and recover compound **2m** (500 mg, 67% yield). 1H-NMR (CDCl3) δ 7.61 (d, *J* = 15.5 Hz, 1H), 7.07 (dd, *J* = 8.5, 1.5 Hz, 1H), 6.95–6.93 (m, 2H), 6.75 (d, *J* = 8.0 Hz, 1H), 6.65–6.62 (m, 2H), 6.49 (d, *J* = 15.5 Hz, 1H), 6.07 (s, 1H), 5.45 (s, 1H), 3.94 (s, 3H), 3.79 (s, 3H), 2.83 (t, *J* = 7.5 Hz, 2H), 2.74 (t, *J* = 7.0 Hz, 2H), 1.38 (s, 6H); 13C-NMR (CDCl3) δ 209.4, 197.7, 148.7, 146.8, 146.3, 144.7, 143.8, 132.6, 126.9, 123.9, 121.0, 118.2, 114.9, 114.2, 111.0, 110.0, 61.7, 56.0, 55.7, 40.7, 29.6, 21.0; HRMS [ESI]<sup>+</sup> calculated for C23H26NaO6: 421.1627 [M + Na]+; found: 421.1233.
