Facile synthesis of 5-substituted-1H-tetrazoles and 1-substituted-1H-tetrazoles catalyzed by recyclable 4′-phenyl-2,2′:6′,2″-terpyridine copper(II) complex immobilized onto activated multi-walled carbon nanotubes

•An easy method for the preparation of a copper nano-structures.•A suitable nano-catalyst for the synthesis of tetrazoles in mild conditions.•Recoverable and reusable heterogeneous catalyst in five runs.

5-Substituted-1H-tetrazoles can conveniently be synthesized from the corresponding nitriles by reaction with NaN3 using the efficient and recyclable heterogeneous catalyst prepared by immobilization of copper(II) complex of 4′-phenyl-2,2′:6′,2″-terpyridine on activated multi-walled carbon nanotubes [AMWCNTs-O–Cu(II)–PhTPY]. Excellent results were obtained in each case affording the corresponding tetrazole adducts in good to excellent yields. In general, aromatic nitriles with electron-donating group could be accomplished as well as that with electron-withdrawing groups. By leaving out nitrile from the reaction and adding CH(OEt)3 and amines bearing various substituents, 1-substituted-1H-tetrazoles formed in water in high yields. The reported protocols have the advantages of rapid assembly of a host of heterocyclic systems in high yields with the added advantage of recycling and reuse of the catalyst.

Graphical abstractA very easy method is described for the immobilization of copper(II) complex of 4′-phenyl-2,2′:6′,2″-terpyridine on activated multi-walled carbon nanotubes [AMWCNTs-O–Cu(II)–PhTPY]. This nano-structure is applied as an efficient and recyclable heterogeneous catalyst for the catalytic synthesis of 5-Substituted-1H-tetrazoles and 1-substituted-1H-tetrazoles in mild conditions.Figure optionsDownload full-size imageDownload as PowerPoint slide