To 1-isocyanato-3-(trifluoromethyl)benzene (9.8 μl, 0.070 mmol) was added a solution of 4-methyl-3-(9H-pyrimido[4,5-b]indol-6-yl)aniline (17.5 mg, 0.064 mmol) and DIPEA (16 μL, 0.089 mmol) in THF (0.4 mL). The reaction was stirred at ambient temperature until LCMS indicated complete reaction, typically 16 hours. The reaction mixture was diluted to a total of 2 mL with THF and MeOH and purified by preparative LCMS to recover the product as a TFA salt (17.1 mg, 46.6%). 1H NMR (300 MHz, DMSO): δ 13.1 (bs, 1H), 9.66 (s, 1H), 9.15 (s, 2H), 8.92 (s, 1H), 8.33 (s, 1H), 8.01 (s, 1H), 7.72 (d, 1H), 7.62 (dd, 1H), 7.4-7.6 (m, 3H), 7.2-7.4 (m, 3H), 2.21 (s, 3H). MS (EI) m/z=462 (M+H).
