Regio-orientation in condensation of aminopyrazoles with 1,3-difunctional reagents: Synthesis of new pyrazolo[1,5-a]pyrimidines; pyrazolo[3,4-d] pyridazines and 2,4-dihydropyrano[2,3-c]pyrazoles

Abstract

Pyrazolo[1,5-a]pyrimidine derivatives were prepared by condensation of 4-phenyldiazenyl-1Hpyrazole-3,5-diamine with enaminonitriles and with enaminones. The regioorientation of reagents was determined by (15N HMBC) measurements as well as NOE difference experiments. A new one-pot synthesis of pyrazolo[3,4-d]pyridazines involving the coupling of N1-[4-cyano-5(3)-(cyanomethyl)-1H-3(5)pyrazoly]acetamide with benzenediazonium chloride is reported. Synthesis of 2,4-dihydropyrano[2,3-c]pyrazole is also reported. ©ARKAT USA, Inc.