4- -Bromo-4-methylpyrazole

Pyrazoles can undergo nitration at several positions 4-bromo-l-methylpyrazole yields the 3,5-dinitro product. 1-Methylpyrazole 2-oxide yields the 5-nitro derivative. 

The halogen atom acts as a functional group more often than others during substitutive nitration. During the nitration of 4-bromo-3-methylpyrazole with a mixture of nitric acid and oleum 3-methyl-4-nitropyrazole is formed [62] (Scheme 46). 4,5-Dibromo-3-methylpyrazole is nitrated similarly [367, 368],... 

Metal-halogen exchange can be achieved in the formation of 3-lithio-l-methylpyrazole from the bromo-pyrazole, and reaction of 4-bromopyrazole with two equivalents of n-butyllithium produces a 1,4-dilithio-pyrazole that reacts with electrophiles at C-4. ° 4-Iodoisothiazole can be converted into a magnesium compound that shows normal nucleophilic Grignard properties. ... 

Coupling 5-isopropyl-l-methylpyrazol-3-ol 333 with 2-bromothi-azole, 5-bromo-pyrimidine and 3-bromoquinoline under Buchwald-type amidation gave pyrazolones 334a-c, in modest yields (06BMCL3713) (Scheme 76). 

Bromo-l-methyl-1//-imidazole, in B-70221 3(5)-Bromo-4-methylpyrazole, B-70250 3(5)-Bromo-5(3)-methylpyrazole, B-70252... 

Bromine added during 5 min. to 4-bromo-l-p-bromophenyl-3-methylpyrazole in 8 N HNO3, and shaken until a dark brown solid is formed 4,5-dibromo-l-p-bromophenyl-3-methylpyrazole. Y 82%. I. L. Finar and D. B. Miller, Soc. 19 1, 2769. 

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