Regioselective synthesis of 2- and 5-trifluoromethyl-or 2- and 5-difluoromethylpyrazolo[1,5-c]pyrimidines based on 7,7,7-trifluoro-or 7,7-difluoro-2,4,6-trioxoheptanoic and 6-trifluoromethyl-or 6- difluoromethylcomanic acids

6-Tri- and 6-difluoromethylcomanic acids and their ethyl esters reacted with aminoguanidine, predominantly giving 5-RF-pyrazolo[1,5-c] pyrimidines, whereas the reaction of the openchain synthetic equivalents, i.e., ethyl 7,7,7-trifluoro- and 7,7-difluoro-2,4,6-trioxoheptanoates, with this polynucleophile allowed us to obtain regioselectively 2-RF- pyrazolo[1,5-c]pyrimidines. © 2012 Springer Science+Business Media New York