* All experimental methods are cited from the reference, please refer to the original source for details. We do not guarantee the accuracy of the content in the reference.
Stage #1: With sodium nitrite In acetic acid at 20℃; Stage #2: With sodium nitrite In water; acetic acid
To a solution of 2-ethyl-6-methylaniline (2.03 g, 15 mmol) in DMF (50 mL) at 0 C was added N-bromosuccinimide (2.66 g, 14.9 mmol). The mixture was stirred at room temperature for 10 minutes before addition to saturated aqueous NaCI. The mixture was extracted with EtOAc, the organic phase was washed with sat aqueous NaCI (2x), concentrated and the crude material was purified by Biotage chromatography (4OM, 15percent EtOAc/heptane) to provide 4-bromo-2-ethyl-6-methylbenzenamine as a red brown liquid (3.21 g, 100percent).A solution of 4-bromo-2-ethyl-6-methylbenzenamine (3.21 g, 15 mmol) in acetic acid (50 mL) was stirred for 3 hours before addition of a 2 M solution of sodium nitrite (11 mL, 22.5 mmol). The resulting mixture was stirred overnight at room temperature. The solution was concentrated and the solid was dissolved in EtOAc and washed with saturated aqueous NaCI (3x). The organic extract was dried over Na2SO4, filtered and concentrated, the crude material was purified by Biotage chromatography (4OM, 15- 30percent EtOAc/heptane) to provide 5-bromo-7-ethyl-1H-indazole (1.11 g, 33percent) and 5-bromo-3,7-dimethyl- 1H-indazole (0.84 g, 25percent).To a solution of 5-bromo-7-ethyl-1H-indazole (225 mg, 1.00 mmol) in dioxane (1.5 mL), hexacarbonylmolybdenum (132 mg, 0.50 mmol), Herrmann's catalyst (trans-Bis(acetato)bis[o-(di-o- tolylphosphino)benzyl]dipalladium) (46.9 mg, 0.05 mmol) and a solution of sodium carbonate (318 mg, 3.00 mmol) in water (2 mL). The suspension was sealed and irradiated in a microwave at 165 0C for 15 minutes (high absorption setting). The vial was vented , filtered through diatomaceous earth, washed with EtOAc and concentrated to provide the title compound (140 mg, 74percent).
Reference：
[1] Journal of Medicinal Chemistry, 2012, vol. 55, # 2, p. 935 - 942
[2] Patent: WO2008/65508, 2008, A1, . Location in patent: Page/Page column 31
2
[ 70598-49-1 ]
[ 635712-49-1 ]
[ 1031417-71-6 ]
Yield
Reaction Conditions
Operation in experiment
33%
Stage #1: With sodium nitrite In acetic acid at 20℃; Stage #2: With sodium nitrite In water; acetic acid
To a solution of 2-ethyl-6-methylaniline (2.03 g, 15 mmol) in DMF (50 mL) at 0 C was added N-bromosuccinimide (2.66 g, 14.9 mmol). The mixture was stirred at room temperature for 10 minutes before addition to saturated aqueous NaCI. The mixture was extracted with EtOAc, the organic phase was washed with sat aqueous NaCI (2x), concentrated and the crude material was purified by Biotage chromatography (4OM, 15percent EtOAc/heptane) to provide 4-bromo-2-ethyl-6-methylbenzenamine as a red brown liquid (3.21 g, 100percent).A solution of 4-bromo-2-ethyl-6-methylbenzenamine (3.21 g, 15 mmol) in acetic acid (50 mL) was stirred for 3 hours before addition of a 2 M solution of sodium nitrite (11 mL, 22.5 mmol). The resulting mixture was stirred overnight at room temperature. The solution was concentrated and the solid was dissolved in EtOAc and washed with saturated aqueous NaCI (3x). The organic extract was dried over Na2SO4, filtered and concentrated, the crude material was purified by Biotage chromatography (4OM, 15- 30percent EtOAc/heptane) to provide 5-bromo-7-ethyl-1H-indazole (1.11 g, 33percent) and 5-bromo-3,7-dimethyl- 1H-indazole (0.84 g, 25percent).To a solution of 5-bromo-7-ethyl-1H-indazole (225 mg, 1.00 mmol) in dioxane (1.5 mL), hexacarbonylmolybdenum (132 mg, 0.50 mmol), Herrmann's catalyst (trans-Bis(acetato)bis[o-(di-o- tolylphosphino)benzyl]dipalladium) (46.9 mg, 0.05 mmol) and a solution of sodium carbonate (318 mg, 3.00 mmol) in water (2 mL). The suspension was sealed and irradiated in a microwave at 165 0C for 15 minutes (high absorption setting). The vial was vented , filtered through diatomaceous earth, washed with EtOAc and concentrated to provide the title compound (140 mg, 74percent).
Reference：
[1] Journal of Medicinal Chemistry, 2012, vol. 55, # 2, p. 935 - 942
[2] Patent: WO2008/65508, 2008, A1, . Location in patent: Page/Page column 31
3
[ 24549-06-2 ]
[ 1031417-71-6 ]
Reference：
[1] Journal of Medicinal Chemistry, 2012, vol. 55, # 2, p. 935 - 942
[2] Patent: WO2008/65508, 2008, A1,
To a solution of 2-ethyl-6-methylaniline (2.03 g, 15 mmol) in DMF (50 mL) at 0 C was added N-bromosuccinimide (2.66 g, 14.9 mmol). The mixture was stirred at room temperature for 10 minutes before addition to saturated aqueous NaCI. The mixture was extracted with EtOAc, the organic phase was washed with sat aqueous NaCI (2x), concentrated and the crude material was purified by Biotage chromatography (4OM, 15% EtOAc/heptane) to provide 4-bromo-2-ethyl-6-methylbenzenamine as a red brown liquid (3.21 g, 100%).A solution of 4-bromo-2-ethyl-6-methylbenzenamine (3.21 g, 15 mmol) in acetic acid (50 mL) was stirred for 3 hours before addition of a 2 M solution of sodium nitrite (11 mL, 22.5 mmol). The resulting mixture was stirred overnight at room temperature. The solution was concentrated and the solid was dissolved in EtOAc and washed with saturated aqueous NaCI (3x). The organic extract was dried over Na2SO4, filtered and concentrated, the crude material was purified by Biotage chromatography (4OM, 15- 30% EtOAc/heptane) to provide 5-bromo-7-ethyl-1H-indazole (1.11 g, 33%) and 5-bromo-3,7-dimethyl- 1H-indazole (0.84 g, 25%).To a solution of 5-bromo-7-ethyl-1H-indazole (225 mg, 1.00 mmol) in dioxane (1.5 mL), hexacarbonylmolybdenum (132 mg, 0.50 mmol), Herrmann's catalyst (trans-Bis(acetato)bis[o-(di-o- tolylphosphino)benzyl]dipalladium) (46.9 mg, 0.05 mmol) and a solution of sodium carbonate (318 mg, 3.00 mmol) in water (2 mL). The suspension was sealed and irradiated in a microwave at 165 0C for 15 minutes (high absorption setting). The vial was vented , filtered through diatomaceous earth, washed with EtOAc and concentrated to provide the title compound (140 mg, 74%).
To a reaction vessel containing a re-purified solution of 5-bromo-3,7-dimethyl-1 H-indazole (prepared as described for Acid Preparation 8, 285 mg, 1.27 mmol) in dioxane (1.3 mL) was added hexacarbonylmolybdenum (264 mg, 1.0 mmol), Herrmann's catalyst (93 mg, 0.1 mmol)and a solution of <n="33"/>Na2CO3 in water (636 mg in 2 mL water). The suspension was heated in a microwave at 165 0C for 15 minutes (high absorption). The vial was vented, acidified with 1 N HCI (to pH 2). The reaction mixture was filtered through diatomaceous earth, washed with EtOAc and the organic layer was washed with saturated aqueous NaCI (3x). The organic extract was concentrated to yield the title compound as a pink solid (65 mg, 17%).
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