Synthesis, X-ray crystallographic analysis, DFT studies and biological evaluation of triazolopyrimidines and 2-anilinopyrimidines

•Design and synthesis of a novel two series of 2-anilinopyrimidines and [1,2,4]triazolo[4,3-a]pyrimidines.•DFT studies gave insights into the mechanism of the [1,2,4]triazolo[4,3-a]pyrimidines cyclisation.•X-ray crystallographic study of two derivatives confirmed the structure of the desired isomer.•Analogs were evaluated for antiviral activity and cytotoxicity.•Compound 14e elicited the best anti-CHIKV activity and the lowest cytotoxicity.