Methyl iodide → 7-Bromo-2,3-dimethyl-2H-indazole

Temperatur

2.5 °C

To a solution of 7-bromo-2-methyl-2H-indazole (5.49 g, 26.0 mmol) in 100 mL of THF at −78° C. was added a 2.0 M solution of lithium diisopropylamide in THF/heptane/ethylbenzene (19.5 mL, 39.0 mmol). The resulting dark orange solution was stirred at 0-5° C. for 15 m, then rechilled at −78° C. for 15 m. Iodomethane (2.5 mL, 40 mmol) was added, and the orange solution allowed to slowly warm to RT over 17 h period with stirring. Water (100 mL) was added, and the mixture was extracted with 100 mL of ether. The organic layer was washed with 200 mL of a saturated aqueous NaCl solution, dried over MgSO4, filtered, and concentrated to an orange solid. Column chromatography (0→50% EtOAc/hexanes) afforded 7-bromo-2,3-dimethyl-2H-indazole (8: R=R″=Me; 5.28 g, 90%) of as a yellow-stained white solid that was used without further purification.

1. customrechilled at −78° C. for 15 m
2. temperatureto slowly warm to RT over 17 h period
3. stirringwith stirring
4. extractionthe mixture was extracted with 100 mL of ether
5. washThe organic layer was washed with 200 mL of a saturated aqueous NaCl solution
6. dry with materialdried over MgSO4
7. filtrationfiltered
8. concentrationconcentrated to an orange solid

ORD-Eintrag

ord-170b7529077a45c38b67620b9649b62e

Quelldatensatz

uspto-grants-2008_04

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US07365211B2