Compound 2.2 (6.35 g, 0.023 mol) in 50 mL of THF at −78° C. was added over 20 min to a solution of LHMDS in THF (25 mL of 1 M solution in THF). After 10 min, 1.1 eq. of 4-methoxybenzyl bromide (25 mmol, 5 mL) was added in one portion. The mixture was stirred at −78° C. for 3 h and then room temperature overnight. Saturated NH4Cl solution was added, the THF was removed in vacuo, 100 mL of Et2O was added and the phases were separated. The organic layer was washed with 50 mL of NaHCO3 solution and brine. After drying (Na2SO4), filtration and removal of the solvent, the residue was purified by chromatography using Si Gel ISCO column with 9% EtOAc in Hexanes as eluent. Concentration of the product fractions gave 7.4 g (82%) of 2.3 as a white solid. MP 128-129° C.; [α]25D=−260 (c 0.8, MeOH); 1H NMR δ 7.27 (1H, d, J=8 Hz), 7.19-7.14 (2H, m), 7.09-7.05 (4H, m), 6.94 (d, 2H, J=8 Hz), 6.76-6.72 (m, 4H), 5.68 (s, 1H), 3.88 (d, 1H, J=12 Hz), 3.86 (s, 3H), 3.27 (d, 1H, J=12 Hz), 2.14 (s, 3H); C NMR 175.1, 169.4, 159.6, 136.7, 131.5, 130.1, 130.0, 128.8, 128.7, 128.2, 127.2, 126.3, 114.6, 90.7, 65.9, 55.8, 40.5, 24.6; ESI MS 402 (M+1).
