Simple and Efficient Three Component One-Pot Synthesis of Pyrazolo[1,5,<i>a</i>]Pyrimidines

Abstract

A series of novel 5-(2-bromophenyl)-N-cyclohexyl-2-(methylthio)-6-nitro-7-phenyl-4,7-dihydropyrazolo[1,5-a]pyrimidine-3-carboxamides were synthesized by a one-pot reaction of 5-amino-N-cyclohexyl-3-(methylthio)-1H-pyrazole-4-carboxamide, 1-(2-bromophenyl)-2-nitroethanone and aryl aldehydes in the presence of boric acid in water at refluxing temperature. Structures of compounds were demonstrated by Fourier transform infrared, 1 H NMR, 13C NMR and elemental analysis. The advantages of this method are mild reaction condition, good yields, and operational simplicity.

A Concise [3 + 3] Heteroaromatization Synthetic Strategy Afford Dicarboxamide Functionalized Novel Pyrazolo[1,5‐a]Pyrimidines

“…This product underwent condensation reaction with carbon disulfide in the presence of base in DMF followed by S‐methylation to afford corresponding 2‐cyano‐3,3‐bis(methylthio)‐ N ‐phenylacrylamide ( 11 ). Cyclization reaction of 11 with hydrazine hydrate yielded 5‐amino‐ N ‐cyclohexyl‐3‐(methylthio)‐1 H ‐pyrazole‐4‐carboxamide ( 12 ) (Scheme 1).…”