Reaction Steps
A solution of C9 (390 mg, 0.762 mmol) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU, 95%, 132 μL, 0.838 mmol) in methanol (15 mL) was heated at 70° C. for 90 minutes. After removal of solvent in vacuo, the residue was purified via silica gel chromatography (Gradient: 0% to 8% methanol in dichloromethane) to provide the product as a solid. Yield: 191 mg, 0.419 mmol, 55%. LCMS m/z 456.2 [M+H]+. 1H NMR (400 MHz, CDCl3) δ 10.40 (br s, 1H), 8.48 (br dd, J=2.7, 0.6 Hz, 1H), 8.31 (dd, J=8.6, 0.6 Hz, 1H), 7.72 (s, 1H), 7.68 (ddt, J=8.6, 2.7, 0.7 Hz, 1H), 6.65 (t, JHF=72.0 Hz, 1H), 3.93 (AB quartet, downfield doublet is broadened, JAB=11.2 Hz, ΔνAB=45.8 Hz, 2H), 3.75 (dqd, J=11.2, 6.1, 2.3 Hz, 1H), 3.19 (dd, J=12.6, 4.0 Hz, 1H), 2.83-2.90 (m, 1H), 2.61 (dd, J=12.6, 2.8 Hz, 1H), 1.81 (ddd, J=13.2, 12.9, 11.4 Hz, 1H), 1.56 (ddd, J=13.4, 4.2, 2.3 Hz, 1H), 1.30 (d, J=6.1 Hz, 3H).
