Reaction Steps
To a dried two-neck 250 mL round bottom flask under argon at −40° C., compound 13 (352 mg, 0.99 mmol) was partially dissolved in CH2Cl2 (30 mL). BBr3 (10 mL, 1.0 M in CH2Cl2, 10 mmol) was added dropwise via an addition funnel under argon. After four hours the reaction was poured onto ice and treated with 5 N NaOH until pH 12. The aqueous solution was isolated and treated with 5 N HCl until pH 7, forming a brown precipitate which was extracted with ethyl acetate (3×40 mL). Extracts were combined, dried with Na2SO4, filtered, concentrated and dried under vacuum to yield 158 mg of an orange solid (61%). NMR: 1H NMR (600 MHz, d6-DMSO): δ 11.840 (s, 1H, N—H), 9.109 (s, 1H, O—H), 8.826-8.816 (dd, J1=4.5, J2=1.5, 2H, pyr-2,6H), 8.063-8.058 (d, J=3.0, 1H, indole-2H), 8.048-8.022 (d, J=15.6, 1H, C═CH), 7.902-7.892 (dd, J1=4.5, J2=1.5, 2H, pyr-3,5H), 7.349-7.346 (d, J=1.8, 1H, indole-4H), 7.307-7.293 (d, J=8.4, 1H, indole-H7), 6.762-6.744 (dd, J1=8.4, J2=2.4, 1H, indole-H6). 13C NMR (150 MHz, d6-DMSO): δ 188.2, 152.9, 150.6, 145.0, 141.4, 134.8, 131.7, 126.0, 121.3, 113.6, 113.1, 112.7, 112.3, 104.9. Melting Point: 262-268° C. TLC (in ethyl acetate:hexane 4:1) Rf=0.35. Elemental analysis calculated for C16H12N2O2.0.1H2O: C, 72.22; H, 4.62; N, 10.53. found: C, 72.21; H, 4.42; N, 10.26.
