An Efficient Synthesis of New 7-Trifluoromethyl-2,5-disubstituted Pyrazolo[1,5-a]pyrimidines

Abstract

A novel two-step synthesis of trifluoromethylated 3,5-disubstituted pyrazolo[1,5-a]pyrimidines is reported from 3-aminopyrazoles and ethyl 4,4,4-trifluorobut-2-ynoate. The synthetic route begins with the one-pot synthesis of 7-trifluoromethylated pyrazolo[1,5-a]pyrimidin-5-ones by condensation of 3-aminopyrazoles with a fluorinated alkyne. The products obtained are used as building blocks to synthesize directly, with excellent yields via C–O bond activation, a library of new fluorinated 3,5-disubstituted pyrazolo[1,5-a]pyrimidines of biological interest. This operation efficiently allows C–C, C–N and C–S bond formation.