A new heterogeneous nano alumina based Cu (II) catalyst for synthesis of 1,4-disubstituted-1,2,3-triazoles

In this research, we synthesized a new heterogeneous catalyst using alumina nanoparticles. This catalyst was synthesized after formation a chain on alumina containing ester groups and then converting to carboxylic acid hydrazide groups. Complexation of Cu (II) with this functional groups yielded nano Al2O3@PCH-Cu(II). Then, a small amount of the catalyst was used to one pot reactions between benzyl bromide derivatives (1 mmol), Phenylacetylene derivatives (1 mmol) and sodium azide (1.5 mmol) in the presence of green solvent (water: ethanol, 1:1) at 50 °C to produce 1,4-disubstitute-1,2,3-triazole derivatives(Scheme 1), the products were obtained with high efficiency in a short time.1,2,3-Triazoles have been widely used in synthetic intermediates and industrial applications, such as dyes, anticorrosive agents, photographic materials, photostabilizers, and agrochemicals[1,2]. Huisgen s thermal 1,3-dipolar cycloaddition of azides and alkynes to synthesis triazoles, was found to be catalyzed by copper(I), these conditions has become the model for click reaction, and is the main method for the synthesis of 1,2,3-triazole. Click chemistry facilitated the reaction at lower temperature and furthermore only the 1,4-disubstituted regioisomer of the 1,2,3-triazole was formed[3]. Copper-catalyzed azide-alkyne cycloaddition (CuAAC) is a type of Huisgen 1,3-dipolar cycloaddition based on the formation of 1,4-disubstituted 1,2,3-triazoles between a terminal alkyne and an aliphatic azide in the presence of copper, and is classified as a ‛click reaction’. Click chemistry promotes the use of organic reactions that allow the connection of two molecular building blocks in a facile, selective, high-yielding reaction under mild reaction conditions with few or no byproducts. Furthermore, this chemistry has the capacity to promote bioconjugation and peptide ligation, stemming from the properties of the triazole linkage as a peptide mimetic. Another analogous RuAAC was reported by Fokin group, which led to the selective formation of 1,5-disubstituted triazole[4].

کلیدواژه ها:

heterogeneous catalyst ، nano alumina ، triazoles: click reaction