Reaction Steps
To a solution of 104 (50 mg, 0.115 mmol) in THF (2.3 mL) under nitrogen at −78° C. was added DIPEA (201 μl, 1.151 mmol) followed by 4-nitrophenyl chloroformate (116 mg, 0.575 mmol). The reaction mixture was kept at −78° C. over 1 hour. 3-(Methylsulfonyl)aniline hydrochloride (143 mg, 0.690 mmol) was added at −78° C. and the reaction mixture was allowed to warm to room temperature slowly. The reaction mixture was then quenched by addition of methanol, concentrated, dissolved in ethyl acetate, and successively washed with NH4Cl and NaHCO3, dried over anhydrous sodium sulfate, filtered and concentrated. The crude product was purified by Biotage (SNAP 25 g cartridge; MeOH/DCM: 0/100 to 20/80 over 20 CV), to afford the title compound 105 (14.8 mg, 0.023 mmol, 20% yield) as beige solid. 1H NMR (400 MHz, DMSO-d6) δ (ppm): 9.28 (s, 1H), 9.21 (s, 1H), 8.54 (d, J=5.6 Hz, 1H), 8.53 (d, J=2.4 Hz, 1H), 8.36 (s, 1H), 8.27 (d, J=8.4 Hz, 1H), 8.18 (t, J=2.0 Hz, 1H), 7.82-7.74 (m, 2H), 7.70 (dt, J=8.0, 1.6 Hz, 1H), 7.59 (t, J=8.0 Hz, 1H), 7.55 (dt, J=8.0, 1.6 Hz, 1H), 7.47 (t, J=8.8 Hz, 1H), 7.31 (d, J=8.8 Hz, 1H), 6.69 (d, J=5.2 Hz, 1H), 4.46 (s, 2H), 3.40-3.28 (m, 2H, hidden under water peak), 3.21 (s, 3H), 2.31 (t, J=8.0 Hz, 2H), 1.95 (quint, J=7.6 Hz, 2H). MS (m/z): 632.5 (M+H).
