4-Amino-2,6-dimethylphenol → 2,6-dimethyl-4-[(2-phenyl-3,4-dihydropyrazol-5-yl)amino]phenol

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Reaction Steps

2,6-dimethyl-4-aminophenol (15 g) and 4,5-dihydro-1-phenyl-1H-pyrazol-3-amine (17.6 g) were heated with p-toluene sulfonic acid (0.2 g) at 160° for 1 hour under nitrogen. The mix was cooled, taken up in dichloromethane and washed with dilute HCl, and water. Evaporation, and chromatography of the residue (silica, dichloromethane/ethyl acetate [9:1]) gave 4-(4,5-dihydro-1-phenyl-1H-pyrazol-3-yl)amino-2,6-dimethylphenol (14.2 g), mp 154°-158°. This was refluxed in toluene (40 ml) with 10% palladium on charcoal (10 g) for 3 hours. The mixture was filtered and evaporated to give, after crystallisation from cyclohexane/ethyl acetate, the title compound (8 g), mp 154°-155°.

Provenance & Evidence