Example 41
Potassium carbonate (110 mg) was added to a solution of Compound 39 (200 mg) and ethyl 2-bromoacetate (100 mg) in DMF (5 mL), and the resulting mixture heated to 80° C. and stirred for 1 h under nitrogen protection. The reaction mixture was cooled to room temperature, and filtered. The filter cake was washed with ethyl acetate (2 mL). The filtrate was concentrated to obtain Compound 42-1. LCMS (ESI) m/z: 606 (M+1).
2) Synthesis of Compound 42-2
An aqueous solution of lithium hydroxide monohydrate (1M, 0.7 mL) was added to a solution of Compound 42-1 (200 mg) in tetrahydrofuran (5 mL), and the resulting mixture was stirred at 26° C. for 1 h under nitrogen protection. The reaction mixture was acidified to pH=5-6 with an aqueous solution of dilute hydrochloric acid (1M), and extracted with ethyl acetate (20 mL×3). The combined organic phase was washed with saturated brine (20 mL), dried over anhydrous sodium sulfate, filtered, and concentrated to obtain Compound 42-2. LCMS (ESI) m/z: 578 (M+1).
3) Synthesis of Compound 42
Methylamine hydrochloride (18 mg) was added to a solution of Compound 42-2 (100 mg), HATU (80 mg), and triethylamine (50 mg, 494.12 μmol) in dichloromethane (5 mL), and the resulting mixture was stirred at 26° C. for 1 h. The reaction mixture was acidified to pH=5-6 with an aqueous solution of dilute hydrochloric acid (1M), and extracted with ethyl acetate (20 mL×3). The combined organic phase was washed with saturated brine (20 mL), dried over anhydrous sodium sulfate, filtered, and concentrated. The residue obtained from the concentration was purified by preparative TLC and preparative HPLC to obtain Compound 42. 1H NMR (400 MHz, CDCl3) δ ppm 8.68 (s, 1H), 7.95 (d, J=8.3 Hz, 1H), 7.88 (d, J=1.5 Hz, 1H), 7.76 (dd, J=8.3, 1.8 Hz, 1H), 7.31-7.36 (m, 1H), 7.29 (dd, J=8.8, 2.0 Hz, 1H), 4.51 (s, 2H), 2.90 (d, J=5.0 Hz, 3H), 2.84 (q, J=7.7 Hz, 2H), 1.62 (s, 6H), 1.29 ppm (t, J=7.5 Hz, 3H); LCMS (ESI) m/z: 591 (M+1).
