3.1.3. *[(1E,6E)-4,4-bis(Hydroxymethyl)-3,5-dioxohepta-1,6-diene-1,7-diyl]bis(2-methoxy-4,1-phenylene) bis[3-hydroxy-2-(hydroxymethyl)-2-methylpropanoate]* (**9**)

A solution of crude **8** (0.34 g) and 6 N HCl (0.15 mL) in MeOH (1.83 mL) was stirred at room temperature for 1 h. The reaction mixture was concentrated under vacuum to give the crude product, which was purified by flash chromatography on silica gel with MeOH/CH2Cl2 (1:20) to afford compound **9** (40 mg) as an orange oil. Yield 6% for two steps. 1H-NMR (DMSO-d6) δ 7.52 (d, *J* = 15.6 Hz, 2H), 7.44 (s, 2H), 7.30 (d, *J* = 8.2 Hz, 2H), 7.08–7.04 (m, 4H), 5.16 (br s, 6H), 4.19 (s, 4H), 3.78 (s, 6H), 3.61 (s, 8H), 1.17 (s, 6H); LRMS [ESI]<sup>+</sup> calculated for C33H40O14: 661.25 [M + H]+; found: 661.4.
