Synthesis of disazo pyrazolo[1,5-a]pyrimidines

Abstract

p-Substituted anilines were diazotized and coupled with 3-aminocrotononitrile, malononitrile, ethyl cyanoacetate or ethyl acetoacetate to give the 2-arylhydrazone-3-ketimino-butyronitriles, 2-arylhydrazonomalononitriles, ethyl 2-arylhydrazonocyanoacetates and ethyl 2-arylhydrazonoacetoacetates, respectively. Cyclization of these arylhydrazone derivatives with 5-amino-4-arylazo-3-methyl-1H-pyrazoles or 3,5-diamino-4-arylazo-1H-pyrazoles in pyridine moiety afforded the corresponding disazo pyrazolo[1,5-a]pyrimidine derivatives. © 2006 Elsevier Ltd. All rights reserved.