{ "text": "Catalyst\n1.35 g H2SO4, 200 mL CH3CN, 4 Å MS (50 mg/mmol), 0 °C to rt, 2 h, then NaHCO3 aq. (50 mL), EtOAc (150 mL x 3). Org. was dried over Na2SO4, filtered, and concentrated in vacuo. Purification by flash chromatography (SiO2, 9:1 hexanes/EtOAc) gave 1.35 g of 51 as a colorless oil (87% yield). 1H NMR (400 MHz, CDCl3) δ 7.84 (d, J = 8.0 Hz, 2H), 7.46-7.40 (m, 3H), 7.39-7.35 (m, 2H), 7.26 (s, 1H), 5.30 (d, J = 8.0 Hz, 1H), 4.80 (dd, J = 8.0, 4.0 Hz, 1H), 4.18-4.12 (m, 1H), 3.97-3.91 (m, 1H), 3.63 (s, 3H), 3.52 (dd, J = 10.0, 6.0 Hz, 1H), 3.41 (dd, J = 10.0, 4.0 Hz, 1H), 2.78-2.72 (m, 1H), 2.53 (dd, J = 16.0, 6.0 Hz, 1H), 2.39 (dd, J = 16.0, 4.0 Hz, 1H), 1.85-1.77 (m, 1H), 1.71-1.63 (m, 1H), 1.53 (s, 9H), 1.45 (s, 9H). HRMS calcd for C20H28N2O6S [M+H]+: 425.1710. Found: 425.1709.\n\n51 13 mg, 0.03 mmol) was dissolved in CH2Cl2 (1 mL) and treated with TFA (0.5 mL). The solution was stirred at rt for 1 h, concentrated in vacuo, and purified by flash chromatography (SiO2, 9:1 CH2Cl2/MeOH) to give 52 as a white solid (13 mg, 0.03 mmol, 97% yield). 1H NMR (400 MHz, CDCl3) δ 8.81 (s, 1H), 7.79 (d, J = 8.0 Hz, 2H), 7.50-7.46 (m, 3H), 7.43-7.39 (m, 2H), 7.28 (s, 1H), 5.38 (d, J = 8.0 Hz, 1H), 4.87 (dd, J = 8.0, 4.0 Hz, 1H), 4.20-4.14 (m, 1H), 4.03-3.97 (m, 1H), 3.65 (s, 3H), 3.54 (dd, J = 10.0, 6.0 Hz, 1H), 3.42 (dd, J = 10.0, 4.0 Hz, 1H), 2.80-2.74 (m, 1H), 2.55 (dd, J = 16.0, 6.0 Hz, 1H), 2.41 (dd, J = 16.0, 4.0 Hz, 1H), 1.87-1.79 (m, 1H), 1.73-1.65 (m, 1H). HRMS calcd for C20H26N2O6S [M+H]+: 423.1553. Found: 423.1552.\n\n52 was treated with HATU (1.0 equiv) and DIPEA (2.0 equiv) in DMF (1 mL) for 30 min at rt. Then, amine 53 (1.0 equiv) was added and the solution stirred at rt for 16 h. The reaction was quenched with H2O (5 mL), extracted with EtOAc (3 x 10 mL), dried over Na2SO4, filtered, and concentrated in vacuo. Purification by flash chromatography (SiO2, 9:1 CH2Cl2/MeOH) gave 54 as a white solid (13 mg, 0.03 mmol, 97% yield). 1H NMR (400 MHz, CDCl3) δ 8.81 (s, 1H), 7.79 (d, J = 8.0 Hz, 2H), 7.50-7.46 (m, 3H), 7.43-7.39 (m, 2H), 7.28 (s, 1H), 5.38 (d, J = 8.0 Hz, 1H), 4.87 (dd, J = 8.0, 4.0 Hz, 1H), 4.20-4.14 (m, 1H), 4.03-3.97 (m, 1H), 3.65 (s, 3H), 3.54 (dd, J = 10.0, 6.0 Hz, 1H), 3.42 (dd, J = 10.0, 4.0 Hz, 1H), 2.80-2.74 (m, 1H), 2.55 (dd, J = 16.0, 6.0 Hz, 1H), 2.41 (dd, J = 16.0, 4.0 Hz, 1H), 1.87-1.79 (m, 1H), 1.73-1.65 (m, 1H). HRMS calcd for C20H26N2O6S [M+H]+: 423.1553. Found: 423.1552.\n\n53 was treated with HATU (1.0 equiv) and DIPEA (2.0 equiv) in DMF (1 mL) for 30 min at rt. Then, amine 54 (1.0 equiv) was added and the solution stirred at rt for 16 h. The reaction was quenched with H2O (5 mL), extracted with EtOAc (3 x 10 mL), dried over Na2SO4, filtered, and concentrated in vacuo. Purification by flash chromatography (SiO2, 9:1 CH2Cl2/MeOH) gave 55 as a white solid (13 mg, 0.03 mmol, 97% yield). 1H NMR (400 MHz, CDCl3) δ 8.81 (s, 1H), 7.79 (d, J = 8.0 Hz, 2H), 7.50-7.46 (m, 3H), 7.43-7.39 (m, 2H), 7.28 (s, 1H), 5.38 (d, J = 8.0 Hz, 1H), 4.87 (dd, J = 8.0, 4.0 Hz, 1H), 4.20-4.14 (m, 1H), 4.03-3.97 (m, 1H), 3.65 (s, 3H), 3.54 (dd, J = 10.0, 6.0 Hz, 1H), 3.42 (dd, J = 10.0, 4.0 Hz, 1H), 2.80-2.74 (m, 1H), 2.55 (dd, J = 16.0, 6.0 Hz, 1H), 2.41 (dd, J = 16.0, 4.0 Hz, 1H), 1.87-1.79 (m, 1H), 1.73-1.65 (m, 1H). HRMS calcd for C20H26N2O6S [M+H]+: 423.1553. Found: 423.1552.\n\n54 was treated with HATU (1.0 equiv) and DIPEA (2.0 equiv) in DMF (1 mL) for 30 min at rt. Then, amine 55 (1.0 equiv) was added and the solution stirred at rt for 16 h. The reaction was quenched with H2O (5 mL), extracted with EtOAc (3 x 10 mL), dried over Na2SO4, filtered, and concentrated in vacuo. Purification by flash chromatography (SiO2, 9:1 CH2Cl2/MeOH) gave 56 as a white solid (13 mg, 0.03 mmol, 97% yield). 1H NMR (400 MHz, CDCl3) δ 8.81 (s, 1H), 7.79 (d, J = 8.0 Hz, 2H), 7.50-7.46 (m, 3H), 7.43-7.39 (m, 2H), 7.28 (s, 1H), 5.38 (d, J = 8.0 Hz, 1H), 4.87 (dd, J = 8.0, 4.0 Hz, 1H), 4.20-4.14 (m, 1H), 4.03-3.97 (m, 1H), 3.65 (s, 3H), 3.54 (dd, J = 10.0, 6.0 Hz, 1H), 3.42 (dd, J = 10.0, 4.0 Hz, 1H), 2.80-2.74 (m, 1H), 2.55 (dd, J = 16.0, 6.0 Hz, 1H), 2.41 (dd, J = 16.0, 4.0 Hz, 1H), 1.87-1.79 (m, 1H), 1.73-1.65 (m, 1H). HRMS calcd for C20H26N2O6S [M+H]+: 423.1553. Found: 423.1552.\n\n55 was treated with HATU (1.0 equiv) and DIPEA (2.0 equiv) in DMF (1 mL) for 30 min at rt. Then, amine 56 (1.0 equiv) was added and the solution stirred at rt for 16 h. The reaction was quenched with H2O (5 mL), extracted with EtOAc (3 x 10 mL), dried over Na2SO4, filtered, and concentrated in vacuo. Purification by flash chromatography (SiO2, 9:1 CH2Cl2/MeOH) gave 57 as a white solid (13 mg, 0.03 mmol, 97% yield). 1H NMR (400 MHz, CDCl3) δ 8.81 (s, 1H), 7.79 (d, J = 8.0 Hz, 2H), 7.50-7.46 (m, 3H), 7.43-7.39 (m, 2H), 7.28 (s, 1H), 5.38 (d, J = 8.0 Hz, 1H), 4.87 (dd, J = 8.0, 4.0 Hz, 1H), 4.20-4.14 (m, 1H), 4.03-3.97 (m, 1H), 3.65 (s, 3H), 3.54 (dd, J = 10.0, 6.0 Hz, 1H), 3.42 (dd, J = 10.0, 4.0 Hz, 1H), 2.80-2.74 (m, 1H), 2.55 (dd, J [TRANSCRIPTION_TRUNCATED_DUE_TO_LOOP]