Nano CaO: Synthesis, characterization, and application as an efficient catalyst for the preparation of tetrazole analogues of protected amino acids

Nano CaO as a recyclable heterogeneous catalyst was synthesized via solution combustion method using Black pepper seed extract as a fuel, calcium nitrate as a source of calcium and characterized by various techniques such as XRD, FT-IR, EDAX, and SEM analysis. The catalyst was established a superior catalytic activity towards the synthesis of tetrazole analogues of protected amino acids in good yield via cycloaddition reaction of sodium azides with protected nitriles in methanol and water system under reflux condition. The synthesized N-protected tetrazoles were characterized by mass, FT-IR, 1H NMR, and 13C NMR. The experiment clarifies the shorter reaction time, inexpensive catalyst which is easily separable by simple filtration, and catalysts can be reused for several times without significant degradation in activity.