Reaction Steps
NaHMDS (1 M in THF, 14.9 mL, 14.9 mmol) was added dropwise over a 30 min period to a cooled (−78° C.) suspension of the imide 25 (7.91 g, 13.6 mmol) in THF (45 mL). After 15 min of stirring, the resulting cold solution was treated with MeI (2.53 mL, 40.8 mmol) and allowed to stir at −78° C. for 3 h before being warmed to 25° C. overnight (12 h) The reaction was quenched with H2O (100 mL), and the aqueous layer was extracted with Et2O (3×150 mL). The combined organic extracts were dried (MgSO4), concentrated in vacuo and chromatographed (EtOAc/hexane 1:9) to provide 5.97 g (74%) of 26 as a colorless oil: 1H NMR (300 MHz, CDCl3) δ 7.42-7.26 (m, 7H), 6.95-6.92 (m, 2H), 4.71 (m, 1H), 4.51 (m, 2H), 4.18 (m, 2H), 3.95 (m, 1H), 3.84 (s, 3H), 3.63 (dd, J=8.9, 3.8 Hz, 1H), 3.57 (dd, J=6.4, 2.7 Hz, 1H), 3.35 (t, J=8.5 Hz, 1H), 3.28 (dd, J=13.3, 3.1 Hz, 1H), 2.83 (dd, J=13.3, 9.4 Hz, 1H), 2.10-1.95 (m, 2H), 1.68 (m, 1H), 1.38 (ddd, J=14.1, 9.8, 4.9 Hz, 1H), 1.31 (d, J=6.8 Hz, 3H), 1.04 (d, J=6.9 Hz, 3H), 0.98 (s, 9H), 0.95 (d, J=6.7 Hz, 3H), 0.14 (s, 3H), 0.13 (s, 3H); 13C NMR (75 MHz, CDCl3) δ 176.8, 158.8, 152.8, 135.1, 130.8, 129.3, 128.9, 128.7, 127.1, 113.5, 77.6, 72.6, 72.4, 65.7, 55.0, 38.9, 38.0, 37.6, 35.3, 33.8, 26.0, 18.8, 18.3, 14.9, 13.8, −3.8, −4.2.
