Boron Derivatives of 3-Methylpyrazole

摘要

The reaction of KBH4 with Hpzme (= 3-methylpyrazole) can be directed to yield K(H2B(pzme)2), K(HB(pzme)3), or K(B(pzme)4), respectively, depending on the experimental conditions. All three salts are sterochemically pure with the methyl group being located exclusively in the 3-position of the pyrazole ring. In contrast, reaction of (CH3)3NBH3 with Hpzme yields a mixture of 1,5- and 1,7-dimethylpyrazabole. Similarly, reaction of K(H2B(pzme)2) with (CH3)3NBH2I produces a mixture of 1,5- and 1,7-dimethylpyrazabole, suggesting at least two different pathways for the latter process. In addition, the compounds 4,4,8,8-tetrabromo- and 4,4,8,8-tetrakis(3-methylpyrazole-1-y1)-1,5(7)-dimethylpyrazabole were also prepared. all compounds were characterized by NMR data.