Click chemistry-assisted synthesis of novel C-2 triazole-linked betulinic acid conjugates with azidothymidine as potential anti-HIV agents

A new synthetic approach to C-2 triazole-linked bioconjugates of lupane triterpenoids with 3'-azido-3'deoxythymidine (AZT) based on Cu I -catalyzed 1,3-cycloaddition between alkynes and azides is described. The proposed strategy towards AZT-betulinic acid hybrid molecules as potential anti-HIV agents makes it possible to vary the C-3 and C-28 pharmacophores in triterpene moieties. The C-2 propargyl-substituted betulinic acid and its mono-or bi-functional derivatives with side chain at C-3 and/or C-28 positions were successfully synthesized by employing the click reaction.