Reaction Steps
Acid 8 (164 mg, 1.00 mmol), benzotriazol-1-yloxy)tripyrrolidinophosphonium hexafluorophosphate (BOP, 884 mg, 2.00 mmol) and DMAP (12 mg, 0.10 mmol) were dissolved in methylene chloride (10 mL) and stirred at room temperature for 10 min. A solution of compound 4 (366 mg, 1.2 mmol) and triethylamine (505 mg, 5.0 mmol) in methylene chloride (15 mL) was added, and the reaction mixture was stirred at room temperature for 48 h. Aqueous work-up and chromatography on silica gel using chloroform and chloroform-methanol (3%) step-gradient as an eluent afforded pure 9 (296 mg, 57%) as orange crystals. 1H NMR (360 MHz, CDCl3): δ 8.18 (d, J=8.6 Hz, 2H), 7.93 (d, J=8.7 Hz, 2H), 7.91 (d, J=8.6 Hz, 2H), 7.43 (d, J=8.3 Hz, 2H), 6.85 (s, 2H), 5.83 (t, J=9.1 Hz, 1H), 4.73 (s, 1H), 4.53 (d, J=5.9 Hz, 2H), 3.96 (s, 3H), 3.11 (septet, J=6.9 Hz, 2H), 2.60 (t, J=7.8 Hz, 2H), 2.29 (t, J=7.6 Hz, 2H), 1.99 (q, J=7.6 Hz, 2H), 1.24 (d, J=6.9 Hz, 12H). 13C NMR (90.55 MHz, CDCl3): δ 173.23, 166.90, 155.42, 152.23, 148.52, 142.66, 133.99, 133.57, 132.17, 130.98, 128.85, 128.38, 123.87, 123.73, 123.01, 121.65, 120.13, 52.73, 43.56, 36.51, 35.45, 28.02, 27.51, 23.15. HRMS (m/z): [M+H]+ calcd. for C31H37N3O4 516.2857. found 516.2863.
