4-Acetyl-3.5-dimethylpyrazole, reaction with

Hydrazino-3-methoxyquinoxaline has been hydrolyzed to quinoxaline-2,3-dione by treatment with boiling 48% HBr or 2% HCl at 140-150 . A series of 2-hydrazino-3-alkoxyquinoxalines gives 2-(2-acetylhydrazino)-3-alkoxyquinoxalines by reaction with l-acetyl-3,5-dimethylpyrazole, and benzoylation of the methylhydrazino compound 2 similarly yields the benzoyl derivative 3." ... 

With an activated C—C triple bond two successive additions can occur if the intermediate alkene is reactive enough. DMAD and 3,5-dimethylpyrazole give an initiaj fumarate (255) which reacts further at the other end to form regioselectively the succinates (256). On the other hand, methyl ethynyl ketone reacts twice at the same carbon atom with pyrazole to form 1,1-pyrazolylbutanone (258) (68ZC458). The probable intermediate, a pyrazolide vinylogue (257), can be prepared from methyl chlorovinyl ketone and pyrazole, in a reaction which is similar to acetylation (Section 4.04.2.1.3(x)). 

The reactions of the completely reduced compounds have attracted much attention because of their close relationship to piperazine. Thus it has been shown, as might be expected, that the 2-position in compounds such as the parent 100 can be readily acetylated and benzoylated" and ureas are formed with phenylisocyanate and phenylisothiocyanate." Compound 100 also reacts at the 2-position with p-acetamidobenzene-sulfonyl chloride to give a sulfonamide. There are several examples of the alkylation of the amine in the 2-position. Various alkyl halides -have been used, as well as ethylene oxide," p-nitrobenzoyl-ethyleneimine, " and l-guanyl-3,5-dimethylpyrazole nitrate. Compound 100 also undergoes the Eschweiler-Clarke modification of the Leuckart reaction to give the 2-methyl compound." ... 

---