4-Carbazol-9-ylmethylbenzoic acid methyl ester (19) (1.0 g, 3.2 mmol) and hydroxylamine hydrochloride (1.3 g, 19.0 mmol) were placed under argon and dissolved in 5 mL of methanol. To it was added a 25% sodium methoxide solution in methanol (5.48 g, 25.4 mmol) which resulted in the formation of a white precipitate. The reaction was stirred for 24 h at room temperature after which the reaction was diluted with 20 mL ethyl acetate and 20 mL of saturated sodium bicarbonate. The organic layer was isolated and the aqueous layer was further extracted with ethyl acetate (2×10 mL). The combined organic layers were washed with brine (10 mL), dried (Na2SO4) and concentrated in vacuo. The crude extract was purified by HPLC to yield the title compound (0.41 g, 41%) as an off-white solid. 1H NMR (400 MHz, DMSO): δ 11.09 (s, 1H), 8.97 (s, 1H), 8.18 (d, 2H, J=7.8 Hz), 7.61 (m, 4H), 7.43 (t, 2H, J=8.0 Hz), 7.19 (m, 4H), 5.71 (s, 2H). 13C NMR (100 MHz, DMSO): δ 164.0, 140.2, 141.1, 132.0, 127.3, 126.8, 126.0, 122.3, 120.5, 119.2, 109.5, 45.4. ESI-HRMS (m/z): [M+H]+ calcd. for C21H17NO2, 317.1149. found, 317.1143. Analytical HPLC: Purity=99%, tR=10.69 min, Method A.
