trans-Crotonyl chloride → HCID 69794715, compound

Participants

Reaction Conditions

Reaction Steps

1.07 cm3 of crotonyl chloride are added to 2 g of 6-bromo-1H-indazole-3-amine, prepared previously, in 30 cm3 of pyridine, cooled to about 3° C. The medium is allowed to return to about 19° C. over 12 hours. The reaction medium is evaporated under reduced pressure (2 kPa; 50° C.) and the residue is taken up in 20 cm3 of ethyl acetate and 20 cm3 of distilled water. The aqueous phase is re-extracted with 20 cm3 of ethyl acetate. The aqueous phases are combined and then evaporated under the conditions described previously. The residue is purified by chromatography under an argon pressure of 50 kPa, on a column of silica gel (particle size 40-60 μm; diameter 2.5 cm), eluting with a cyclohexane/ethyl acetate mixture (50/50 by volume) and collecting 15 cm3 fractions. The fractions containing the expected product are combined and evaporated under reduced pressure (2 kPa; 50° C.). After drying (90 Pa; 45° C.), 130 mg of N-(6-bromo-1H-indazol-3-yl)-2-butenamide (E form) are obtained in the form of a beige-coloured solid melting at 232° C.

Provenance & Evidence