2,6-Lutidine → ethyl (+/-)-10,11-dihydro-3-(trifluoromethanesulfonyioxy)-5H-dibenzo[a,d]cycloheptene-10-acetate

Participants

Reaction Steps

Trifluoromethanesulfonic anhydride (0.45 mL, 2.68 mmol) was added dropwise to a solution of ethyl (±)-10,11-dihydro-3-hydroxy-5H-dibenzo[a,d]cycloheptene-10-acetate (611.7 mg, 2.06 mmol) and 2,6-lutidine (0.48 mL, 4.12 mmol) in anhydrous CH2Cl2 (10.3 mL) at −78° C. under argon. After 0.5 h, the reaction was warmed to RT and stirred for 1 h. The yellow solution was diluted with Et2O (50 mL) and washed sequentially with 1.0 N HCl (5 mL), 5% NaHCO3 (5 mL), and brine (5 mL). Drying (MgSO4), concentration, and silica gel chromatography (20% EtOAc/hexanes) gave the title compound as a colorless oil (808.9 mg, 92%): TLC Rf (20% EtOAc/hexanes) 0.58; 1H NMR (250 MHz, CDCl3) δ 6.98-7.30 (m, 7H), 4.35 (d, J=15.2 Hz, 1H), 4.19 (q, J=7.1 Hz, 2H), 3.91 (d, J=15.2 Hz, 1H), 3.78-3.95 (m, 1H), 3.37 (dd, J=15.2, 4.1 Hz, 1H), 3.02 (dd, J=15.2, 9.6 Hz, 1H), 2.70 (dd, J=15.8, 4.8 Hz, 1H), 2.53 (dd, J=15.8, 9.6 Hz, 1H), 1.27 (t, J=7.1 Hz, 3H); FTIR (CCl4) 1735, 1493, 1427, 1250, 1215, 1144, 961, 856 cm−1; MS (ES) m/e 451.1 (M+Na)+, 446.2 (M+NH4)+, 429.2 (M+H)+.

Provenance & Evidence