Reaction Steps
Triethylsilane (3.84 mL, 24.1 mmol) was added to a stirring, room temperature solution of 71 (2.1400 g, 7.77 mmol) in trifluoroacetic acid (TFA) (18.5 mL, 0.42 M) under N2. When the reaction was judged complete by HPLC, the TFA was removed under vacuum, and the crude product was taken up in EtOAc, washed with brine, dried with Na2SO4, filtered, concentrated, and purified by preparative reverse phase HPLC with the following conditions: 0 to 12 min, 35:65 H2O:CH3CN; 14-15 min, 35:65 to 0:100 H2O:CH3CN; 20 mL/min.; λ=254 nM; 3.67 g/mL, 0.2 mL/injection. 1.1571 g (57.0%) of 72 was obtained as a fluffy white solid. (Note: An undesired impurity has a retention time of 11.414 min by HPLC.) 1H (CDCl3, 400 MHz): δ 9.33 (1H, broad s), 7.13 (2H, dd, J=8.5, 5.6 Hz), 6.96 (2H, t, J=8.8 Hz), 6.79 (1H, s), 6.66 (1H, s), 4.33 (2H, t, J=7.1 Hz), 2.86 (2H, t, J=7.1 Hz), 2.77 (2H, t, J=7.1 Hz), 1.36 (3H, t, J=7.1 Hz) ppm. 13C (CDCl3, 100 MHz): 6161.31, 161.22 (d, J=242 Hz), 137.46 (d, J=3.2 Hz), 129.71 (d, J=7.7 Hz), 125.22, 122.52, 120.84, 114.89 (d, J=21.9 Hz), 114.79, 60.19, 36.44, 28.73, 14.37 ppm. DEPT (CDCl3, 100 MHz): CH3 carbons: 14.37; CH2 carbons: 60.19, 36.44, 28.73; CH carbons: 129.71 (d, J=7.7 Hz), 120.84, 114.89 (d, J=21.9 Hz), 114.79 ppm. HPLC: 10.797 min.
