3.1.4. *[(1E,6E)-4,4-bis(Acetoxymethyl)-3,5-dioxohepta-1,6-diene-1,7-diyl]bis(2-methoxy-4,1-phenylene) bis[3-hydroxy-2-(hydroxymethyl)-2-methylpropanoate]* (**10**)

To a stirred solution of crude **8** (0.450 g) in DCM (10 mL) were added NEt3 (1.0 mL) and acetyl chloride (0.140 g, 1.81 mmol) at 0 ◦C. The reaction mixture was warmed to room temperature and stirred for 12 h. Then H2O (10 mL) and diluted HCl(aq) (1 *N*, 3 mL) were added to quench the reaction. The aqueous layer was separated and extracted with CH2Cl2 (3 × 8 mL). The combined organic extracts were washed with brine, dried over MgSO4, filtered and concentrated to give the crude product, which was then treated with HCl(aq) (6 *N*, 0.2 mL) in MeOH (2 mL) at room temperature. The reaction mixture was stirred at room temperature for 1h and then concentrated under vacuum to give the crude product, which was purified on silica gel with MeOH/CH2Cl2 (1:20) to afford **10** (33 mg) as a yellow solid (mp = 194–196 ◦C). Yield 3% for three steps; 1H-NMR (DMSO-d6) δ 7.68 (d, *J* = 15.5 Hz, 2H), 7.51 (s, 2 H), 7.37 (d, *J* = 8.0 Hz, 2H), 7.20 (d, *J* = 15.5 Hz, 2H), 7.08 (d, *J* = 8.5 Hz, 2H), 4.85 (t, *J* = 5.0 Hz, 8H), 3.80 (s, 6 H), 3.65-3.59 (m, 8H), 1.97 (s, 6H), 1.19 (s, 6H); 13C-NMR (DMSO-d6) δ 193.1, 173.3, 170.5, 151.7, 144.6, 142.5, 132.9, 123.9, 122,7, 121.7, 113.6, 64.0, 61.9, 56.7, 51.0, 20.9, 17.3; HRMS [ESI]<sup>+</sup> calculated for C37H44NaO16: 767.2527 [M + Na]+; found: 767.2521.
