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A solution OF 4-BROMO-5-ISOPROPYL-LH-INDAZOLE (1.6 g, 6.9 mmol) in Et2O (4 mL) is added slowly to a suspension OF KH (1.0 g of 30 % dispersion in mineral oil, 7.7 mmol) in Et20 (20 ML) at 0 C and the mixture is stirred for 20 minutes. After cooling TO-78 C, T- BuLi (8.9 mL of 1.7 M in Hex, 15 mmol) is added and the resulting mixture is stirred for 40 minutes AT-78 C. To this is added B (ON-BU) 3 (5.6 mL, 21 mmol) and the mixture is stirred for 24 hours at room temperature. The reaction mixture is quenched with IN H3P04 and extracted with Et2O. The combined Et20 layers are back-extracted with IN NAOH (3 * 10 mL). The combined NAOH extracts are acidified with IN H3P04 and extracted with EtOAc. The EtOAc extracts are washed with saturated brine, dried (MgS04), and concentrated to yield 5-ISOPROPYL-LH-INDAZOLE-4-BORONIC ACID. 1H NMR (CDCI3) 7. 85 (s, 1H), 7.42 (d, 1H), 7. 37 (d, 1H), 3.6 (br s, 2H), 2.88 (m, 1H), 1.32 (d, 6H). |
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A solution of 4-bromo-5-isopropyl-l/J-indazole (1.6 g, 6.9 mmol) in Et2O (4 mL) is added slowly to a suspension of KH (1.0 g of 30 % dispersion in mineral oil, 7.7 mmol) in Et2O (20 mL) at 0 C and the mixture is stirred for 20 min. After cooling to -78 C, /-BuLi (8.9 mL of 1.7 M in Hex, 15 mmol) is added and the resulting mixture is stirred for 40 min at -78 C. To this is added B(O«-Bu)3 (5.6 mL, 21 mmol) and the mixture is stirred for 24 h at room temperature. The reaction mixture is quenched with IN H3PO4 and extracted with Et2O. The combined Et2O layers are back-extracted with IN NaOH (3x10 mL). The combined NaOH extracts are acidified with IN H3PO4 and extracted with EtOAc. The EtOAc extracts are washed with saturated brine, dried (MgSO4), and concentrated to yield 5-isopropyl-lNo.-indazole-4-boronic acid. 'H NMR (CDC13) 7.85 (s, 1H), 7.42 (d, 1H), 7.37 (d, 1H), 3.6 (br s, 2H), 2.88 (m, 1H), 1.32 (d, 6H). |
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A solution of 4-bromo-5-isopropyl-IH-indazole (1.6 g, 6.9 mmol) in EtzO (4 mL) is added slowly to a suspension of KH (1.0 g of 30 % dispersion in mineral oil, 7.7 mmol) in Et2O (20 mL) at 0 C and the mixture is stirred for 20 min. After cooling to -78 C, t-BuLi (8.9 mL of 1.7 M in Hex, 15 mmol) is added and the resulting mixture is stirred for 40 min at -78 C. To this is added B(On-Bu)3 (5.6 mL, 21 mmol) and the mixture is stirred for 24 h at room temperature. The reaction mixture is quenched with IN H3P04 and extracted with Et2O. The combined Et2O layers are back-extracted with IN NaOH (3 x 10 mL). The combined NaOH extracts are acidified with IN H3P04 and extracted with EtOAc. The EtOAc extracts are washed with saturated brine, dried (MgS04), and concentrated to yield 5-isopropyl-IH-indazole-4-boronic acid. 'H NMR (CDC13) 7.85 (s, 1H), 7.42 (d, 1H), 7.37 (d, 1H), 3.6 (br s, 2H), 2.88 (m, 1H), 1.32 (d, 6H). |