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-bromo-4-methyl-5-nitro-lH-indazoleTo a heated at reflux solution of of 4-methyl-5-nitro-lH-indazole (1.77 g, 10 mmol) in MeOH (30 mL) was added Br2 (1.6 g, 10 mmol) slowly. The reaction was refluxed for 1 h, concentrated, and the residue was washed with Na2C03 aq., extracted with (¾(-¾. The organic layer was washed with brine twice, dried over Na2S04, concentrated to give 3-bromo-4-methyl- 5-nitro-lH-indazole as a yellow solid (2.5 g, 97%). NMR (300 MHz, DMSO-d6) delta 7.89 (d, 7=9.09 Hz, 1 H), 7.53 (d, 7=9.09 Hz, 1 H), 2.87 (s, 3 H).
4-methyl-5-nitro-1-tetrahydropyran-2-yl-indazole[ No CAS ]
Yield
Reaction Conditions
Operation in experiment
97%
With toluene-4-sulfonic acid; In dichloromethane; for 16.0h;
A suspension of <strong>[101420-67-1]4-methyl-5-nitro-1H-indazole</strong> (1.00 g, 5.64 mmol) in DCM (10 mL) was treated with 3,4-dihydro-2H-pyran (1.55 mL, 16.93 mmol) and PTSA (107 mg, 0.56 mmol). After 16 h LCMS showed full conversion. The reaction mixture was diluted with sat. aq. NaHCO3 and extracted three times with DCM. The combined organic layers were passed through a phase separator and concentrated in vacuo. Purification by flash column chromatography (80 g SiO2, EtOAc/heptane -10% to 30%) gave 4-methyl-5-nitro-1-tetrahydropyran-2-yl-indazole (1.42 g, 5.45 mmol, 97% yield) as an orange amorphous solid. UPLC-MS (ES+, Method A): 1.80 min, m/z 262.1 [M+H]+