One-pot PTC synthesis of polyfused pyrazoles

Abstract

Thienopyrazole 2, 3, 5, or 6 and thienopyrazolothiazepine 7, 9, and 11 derivatives were prepared via the reaction of the 3-aminopyrazoline-5-one 1 with CS2 and different molar ratio of a variety of halo compounds having an active methylene under PTC conditions. Also, treatment of 1 with CS2 and alcoholic KOH in 2:1:1 molar ratio afforded dipyrazolopyridine derivatives 12 and 14. On other hand, the pyrazolothiadiazineone derivative 13 was obtained by treating compound 1 with CS2 and alcoholic KOH in 1:2:2 molar ratio. Under PTC conditions, compound 1, CS2, and ethyl cyanoacetate or malononitrile to gave the pyrazolopyridine derivatives 16 and 17. Coupling of compound 1 with diazonium acetates afforded the hydrazone derivatives 18a,b, which were oxidized with bromine to give pyrazolotriazoles 19a,b or cyclized with aldehydes to give pyrazolotriazine derivatives 20a-e. Bromination of compound 1 afforded monobromopyrazole derivative 21, which could be condensed to a dipyrazolopyrazindione 23. Finally, the dibromopyrazole derivative 22 was cyclized with 2-mercaptoethanol or o-phenylenediamine to give the spiropyrazoles 24a,b. © 2003 Wiley Periodicals, Inc.