Tetrahydrofuran → 3-Amino-6,7-difluoro-1H-indazole

Participants

Reaction Conditions

Reaction Steps

0.32 cm3 of hydrazine monohydrate is added to 0.46 cm3 of 2,3,4-trifluorobenzonitrile in 10 cm3 of absolute ethanol. The medium is heated at about 75° C. for 17 hours and then 10 cm3 of ethyl acetate, 5 cm3 of tetrahydrofuran and 5 cm3 of distilled water are added. The organic phase is separated out after settling of the phases has taken place, and is washed again with 10 cm3 of distilled water and then with 10 cm3 of saturated aqueous sodium chloride solution. The organic phase is separated out after settling of the phases has taken place, dried over magnesium sulphate, filtered and concentrated to dryness under reduced pressure (2 kPa; 50° C.). The residue obtained is purified by chromatography under an argon pressure of 50 kPa, on a column of silica gel (particle size 40-60 μm; diameter 1.5 cm), eluting with a cyclohexane/ethyl acetate mixture (50/50 by volume). The fractions containing the expected product are combined and then evaporated under reduced pressure (2 kPa; 40° C.); after drying (90 Pa; 40° C.), 100 mg of 6,7-difluoro-1H-indazole-3-amine are obtained in the form of a white solid melting at 183° C.

Provenance & Evidence