3.1.1. *[(1E,6E)-4,4-Diallyl-3,5-dioxohepta-1,6-diene-1,7-diyl]bis(2-methoxy-4,1-phenylene) bis[3-hydroxy-2-(hydroxymethyl)-2-methylpropanoate]* (**6**)

Mp = 195–197 ◦C; 1H-NMR (DMSO-d6) δ 7.59 (d, *J* = 15.5 Hz, 2H), 7.48 (s, 2H), 7.35 (dd, *J* = 8.2, 1.5 Hz, 2H), 7.12–7.04 (m, 4H), 5.59–5.52 (m, 2H), 5.12–5.04 (m, 4H), 4.82–4.80 (m, 4H), 3.78 (s, 6H), 3.60 (s, 8H), 2.84 (d, *J* = 7.2 Hz, 4H), 1.17 (s, 6H); 13C NMR (DMSO-d6) δ 196.8, 173.3, 151.7, 143.1, 142.1, 133.3, 133.2, 123,9, 122.9, 122.8, 119.5, 113.4, 67.4, 64.0, 56.7, 51.0, 35.0, 17.3; HRMS [ESI]<sup>+</sup> calculated for C37H45O12: 681.2911 [M + H]+; found: 681.2903.

3.1.2. *[(1E,6E)-4,4-bis(Hydroxymethyl)-3,5-dioxohepta-1,6-diene-1,7-diyl]bis(2-methoxy-4,1-phenylene) bis(2,2,5-trimethyl-1,3-dioxane-5-carboxylate)* (**8**)

To a stirred solution of **7** (1.00 g, 1.47 mmol) in THF (7.3 mL, containing 0.6 M formaldehyde) was added DBU (38.9 mg, 0.04 mmol) at 0 ◦C. The reaction mixture was stirred at the same temperature for 30 min and then warm to room temperature. After 2 h, the solution was concentrated under vacuum to provide crude compound, which was identified by LRMS [ESI]<sup>+</sup> calculated for C39H49O14: 741.31 [M + H]+; found: 741.33 and used for next step without purification.
