Synthesis of 4-acetyl-5(3)-amino-3(5)-methylpyrazoles and pyrazolo[3,4-d]pyrimidines from diacetylketeneN,S-acetal
摘要:
Isomeric 4-acetyl-5-amino-3-methyl- and 4-acetyl-3-amino-5-methylpyrazoles (2, 3) were formed in the reaction of hydrazines with 3-[amino(methylthio)methylene]pentan-2,4-dione (1) (diacetylketene NS-acetal). Pyrazolo[3,4-d]pyrimidines (5a,b) were synthesized by condensation of 4-acetyl-5-amino-1,3-dimethylpyrazole (2a) with amide dimethylacetals followed by treatment with ammonium acetate. The structures of the compounds obtained were confirmed by C-13 and N-15 NMR spectroscopy.
of enolisable ketones with 1-alkyl-1-cyanohydrazines leads to the corresponding cyanohydrazones. These compounds cyclise under thermal or mildly basic conditions, furnishing the corresponding 5-aminopyrazoles in good yield. In some cases, the hydrazones cannot be isolated, and the pyrazole derivatives are directly obtained. Hydrazone-enehydrazine tautomerism was observed, but no subsequent [3,3] rearrangement
Synthesis of 4-acetyl-5(3)-amino-3(5)-methylpyrazoles and pyrazolo[3,4-d]pyrimidines from diacetylketeneN,S-acetal
作者:V. A. Dorokhov、A. V. Komkov、B. I. Ugrak
DOI:10.1007/bf00699932
日期:1993.8
Isomeric 4-acetyl-5-amino-3-methyl- and 4-acetyl-3-amino-5-methylpyrazoles (2, 3) were formed in the reaction of hydrazines with 3-[amino(methylthio)methylene]pentan-2,4-dione (1) (diacetylketene NS-acetal). Pyrazolo[3,4-d]pyrimidines (5a,b) were synthesized by condensation of 4-acetyl-5-amino-1,3-dimethylpyrazole (2a) with amide dimethylacetals followed by treatment with ammonium acetate. The structures of the compounds obtained were confirmed by C-13 and N-15 NMR spectroscopy.