Methylhydrazine → 4-Bromo-1-methyl-1H-indazole

Temperature

80 °C

A solution of crude 2-bromo-6-fluorobenzaldehyde (42 g, 0.2 mol) (XXV) in DMSO (44 mL) was added to methylhydrazine (63 g, 7 eq) while maintaining the internal temperature to less than 35° C. The mixture was then heated to 80° C. for 22 hours, after which the internal temperature was adjusted to 25° C. The mixture was diluted with water (160 mL) and heptanes (160 mL) while maintaining the internal temperature at less than 40° C. The layers were separated, and the aqueous layer was extracted with heptanes (40 mL). Combined organic layers were washed with 10% citric acid (100 mL) and concentrated in vacuo. The product solidified on standing to give a yellowish solid (27.5 g, 70% yield)

1. temperaturewhile maintaining the internal temperature to less than 35° C
2. customwas adjusted to 25° C
3. temperaturewhile maintaining the internal temperature at less than 40° C
4. customThe layers were separated
5. extractionthe aqueous layer was extracted with heptanes (40 mL)
6. washCombined organic layers were washed with 10% citric acid (100 mL)
7. concentrationconcentrated in vacuo

ORD record

ord-9d6922d080964f499f893311b9478efa

Source dataset

uspto-grants-2012_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08232411B2