Synthesis of 2-hydroxy-7-[benzimidazol-2-yl]methyl-5-methylpyrazolo[1,5-a]pyrimidines from 4-hydroxy-6-methylpyran-2-one

Condensation of 3-amino-5-hydroxypyrazole 1 with triacetic acid lactone 2 i n refluxed alcohols afforded 2-hydroxy-5,7-dimethylpyrazolo[1 :5-a]pyrimidi ne 3 beside to 7-alkoxycarbonylmethyl-2-hydroxy-5-methylpyrazoio[1,5-a]pyri midine 4, Action of hydrazine on compounds 4 yielded 7-hydrazinocarbonylmet hyl-2-hydroxy-5-methlylpyrazolo[1,5-a]-pyrimidines 5. Condensation of o-phe nylenediamines 6 with hydrazide 5 to melting reactants afforded 2-hydroxy-7 -[benzimidazol-2-yl]methyl-5-ethylpyrazo[1,5-a]pyrimidines 7. Structures of the obtained products have been assigned by means of spectroscopic measure ments. (C) 2001 Academie des sciences / Editions scientifique et medicales Elsevier SAS.