A Star-Shaped Triazine-Based Vitamin B5 Copper(II) Nanocatalyst for Tandem Aerobic Synthesis of Bis- (indolyl)methanes

Abstract

In this work, the catalytic efficiency of a novel biorelevant triazine (TA)-based pantothenate (vitamin B5) copper(II) complex [Cu(II)-TA/B5] in the aerobic oxidation of benzyl alcohols and tandem synthesis of bis(indolyl)methanes was exploited. The star-shaped catalyst was characterized by different techniques such as FT-IR, EDX, ICP, TEM, and TGA. TEM images revealed a honeycomb structure resulting from the accumulation of nanoparticles with size ranging between 2–6 nm. The Introduction The use of biologically active materials has always been the ultimate source of inspiration for scientists working across all disciplines. Among these, biocatalysts, an emerging group of catalysts, which facilitate the syntheses of complex organic molecules by chemo-, region-, and stereoselective bond-forming reactions are of extreme interest.[1] Because of high turnover numbers and frequencies, mild reaction conditions, high product selectivity, and low environmental impact, biocatalysts have been employed for both simplified chemical synthesis routes and improved outcomes.[2] Vitamins constitute a group of chemically unrelated organic compounds that are necessary for all animals to maintain normal metabolic functions. They are different from other biological compounds because they generally cannot be synthesized in amounts sufficient to meet bodily needs and hence must be supplied in the diets. Relatively small quantities of vitamins are needed to complete their functions, which are of a catalytic or regulatory nature, facilitating or controlling vital chemical reactions in the body′s cells.[3] Vitamin B5, also known as pantothenic acid, is an essential vitamin consists of pantoic acid and [a] B. Hasanpour, Prof. Dr. M. Jafarpour, Dr. A. Eskandari, Prof. Dr. A. Rezaeifard Catalysis Research Laboratory, Department of Chemistry, Faculty of Science, University of Birjand, Birjand, 97179-414 Iran E-mail: mjafarpour@birjand.ac.ir (M. Jafarpour) http://cv.birjand.ac.ir/jafarpour/en E-mail: rrezaeifard@birjand.ac.ir (A. Rezaeifard) http://cv.birjand.ac.ir/rezaeifard/en Supporting information and ORCID(s) from the author(s) for this article are available on the WWW under https://doi.org/10.1002/ejoc.202000270. Eur. J. Org. Chem. 2020, 4122–4129 4122 © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim high yields and excellent selectivity were obtained for the production of various benzaldehydes and bis(indolyl)methanes under aerobic conditions. Recycling tests, spectroscopic data, and leaching experiments testified that the title heterogeneous biorelevant catalyst preserved its activity and structural integrity during oxidation and coupling reactions. The presented catalytic systems qualify all requirements for efficient catalytic systems for applied goals.