Cu(ii) PBS-bridged PMOs catalyzed one-pot synthesis of 1,4-disubstituted 1,2,3-triazoles in water through click chemistry

Abstract

A series of PBS-HPMO and Cu(II)-PBS-HPMO were synthesized from the self-assembly of 1,2-bis(triethoxysilyl)ethane and porphyrin-bridged silsesquioxane (PBS). These synthesized PBS-HPMO and Cu(II)-PBS-HPMO were characterized using different spectroscopic and non-spectroscopic techniques, namely, XRD, FT-IR spectroscopy, nitrogen adsorption–desorption isotherms, and UV-visible and EPR spectroscopies. Among these, the porphyrin-bridged PMOs, specifically Cu(II)-PBS-HPMO, were found to be proficient catalysts for the multicomponent reaction of benzyl halides with sodium azide and terminal alkynes. This catalyst allowed for the high regioselective synthesis of 1,4-disubstituted 1,2,3-triazoles through a one-step and atom economic tandem reaction with water as the solvent. Note that no additional base or ligand or reducing agent is required. Moreover, in addition to benzyl halides, hetero benzyl halides have also been achieved in remarkable yields and in a completely regioselective manner. A series of structurally diverse 1,2,3-triazoles were also prepared in good to excellent yields from easily accessible starting materials by employing this protocol. Furthermore, this process is purely heterogeneous and the cascade reactions were performed in water, and the efficient catalyst recyclability makes such a synthesis a truly green process.