“…Mixture of Compounds 15a and 15b : Mixture 11 (70 mg, 0.23 mmol), N , N -dimethylaminopyridine (3.1 mg, 0.025 mmol), triethylamine (0.051 g, 0.51 mmol) and acetic anhydride (0.126 g, 1.26 mmol) were stirred for 18 h at 70 °C; the mixture was partitioned between diethylether and ammonium bicarbonate (10%) and the organic phase was purified by silica-gel column using a gradient of petroleum ether/diethylether to obtain the acetate intermediate 14 [ 18 ], that was dissolved in methanol (0.5 mL) and sodium bicarbonate (saturated) buffer solution (0.5 mL) of Oxone ® (0.052 mmol); after stirring at 25 °C for 7 h, methanol (0.5 mL), water (0.5 mL) and oxone (0.052 mmol) were added and the mixture was kept under stirring overnight; after partition between water and chloroform, the organic phase was purified by silica-gel column using a gradient of petroleum ether and diethylether to give 15 as a mixture of regioisomers (9 mg, 0.0276 mmol, 12%); R f (Petroleum ether/diethyl ether 6/4) = 0.1; 1 H-NMR (400 MHz, C 6 D 6 ): δ = 6.64 (dd, J = 15.7, 4.5 Hz, 1H), 6.23 (dd, J = 15.7, 1.4 Hz, 1H), 3.79 (m, 1H), 3.39 (s, 3H; OCH 3 ), 2.28 (t, J = 7.2 Hz, 2H), 2.06 (t, J = 7.2 Hz, 2H; H2), 1.69 (m, 2H), 1.51 (m, 2H), 1.30-1.11 (m, 16H), 0.89 (t, J = 6.2, 3H; H 3 18); 13 C-NMR (100MHz, C 6 D 6 ): δ = 199.2 (C), 147.2 (CH), 128.0 (CH), 70.9 (CH), 51.0 (OCH 3 ), 41.03 (CH 2 ), 36.7 (CH 2 ), 33.9 (CH 2 ), 32.1 (CH 2 ), 30.3 (CH 2 ), 29.8 (CH 2 ), 29.6 (CH 2 ), 29.1 (CH 2 ), 25.1 (2 CH 2 ), 24.4 (CH 2 ), 23.0 (CH 2 ), 14.3 (CH 3 ). UV λ max (MeOH) 219 nm (ε = 1570); HRMS (ESI + ): m/z calcd for C 19 H 34 O 4 Na: 349.2355; found: 349.2359.…”