Synthesis and In Vitro Cytotoxicity and Antibacterial Activity of Novel 1,2,3-Triazol-5-yl-phosphonates

A New Insight Into The Huisgen Reaction: Heterogeneous Copper Catalyzed Azide-Alkyne Cycloaddition for the Synthesis of 1,4-Disubstituted Triazole (From 2018-2023)

The Huisgen cycloaddition, often referred to as 1,3-Dipolar cycloaddition, is a well-established method for synthesizing 1,4-disubstituted triazoles. Originally conducted under thermal conditions [3+2] cycloaddition reactions were limited by temperature, prolonged reaction time, and regioselectivity. The introduction of copper catalyzed azide-alkyne cycloaddition (CuAAC) revitalized interest, giving rise to the concept of "click chemistry". The CuAAC has emerged as a prominent method for producing 1,2,3-triazole with excellent yields and exceptional regioselectivity even in unfavorable conditions. Copper catalysts conventionally facilitate azide-alkyne cycloadditions, but challenges include instability and recycling issues. In recent years, there has been a growing demand for heterogeneous and porous catalysts in various chemical reactions. Chemists have been more interested in heterogenous catalysts as a result of the difficulties in separating homogenous catalysts from reaction products. These catalysts are favored for their abundant active sites, extensive surface area, easy separation from reaction mixtures, and the ability to be reused. Heterogeneous catalysts have garnered significant attention due to their broad industrial utility, characterized by cost-effectiveness, stability, resistance to thermal degradation, and ease of removal compared to their homogeneous counterparts. The present review covers recent advancements from year 2018 to 2023 in the field of click reactions for obtaining 1,2,3-triazoles through Cu catalyzed 1,3-dipolar azide-alkyne cycloaddition and the properties of the catalyst, reaction conditions such as solvent, temperature, reaction time, and the impact of different heterogeneous copper catalysts on product yield.

Naphthalen-2-yl 1-(benzamido(diethoxyphosphoryl)methyl)-1H-1,2,3-triazole-4-carboxylate

We have previously published new biheterocyclic phospohonic α-amino esters of the 1,2,3-triazole-benzimidazole and 1,2,3-triazole-carbazole type. The aim of the present paper was to describe a new phosponic aminoester bearing a triazole ring substituted in position 5 by an ester group. Thus, according to the same catalytic process used previously, the compound naphthalen-2-yl 1-(benzamido(diethoxyphosphoryl)methyl)-1H-1,2,3-triazole-4-carboxylate was synthesized with an excellent yield and high regioselectivity via the copper (I)-catalyzed alkyne–azide cycloaddition reaction (CuAAC), using diethyl (α-azido(benzamido)methyl)phosphonate (1) as a dipole and 2- naphthyl propiolate as a dipolarophile (2). The structure of the new compound was fully characterized by 1D (31P, 1H-, 13C-) and 2D (1H-1H and 1H-, 13C-) NMR spectroscopy, IR, and HRMS.

Synthesis of 3,4-Dihydropyrimidin-2(1H)-one-phosphonates by the Microwave-Assisted Biginelli Reaction

The synthesis of novel 3,4-dihydropyrimidin-2(1H)-one-phosphonates was elaborated by the microwave (MW)-assisted three-component Biginelli reaction of β-ketophosphonates, aromatic or aliphatic aldehydes and urea derivatives. The condensation was optimized on a selected model reaction in respect of the reaction parameters, such as the heating method, the type of the catalyst and solvent, the temperature, the reaction time and the molar ratio of the starting materials. The fast and solvent-free MW-assisted procedure was then extended for the preparation of further new 3,4-dihydropyrimidin-2(1H)-one-phosphonate derivatives starting from different aromatic aldehydes, β-ketophosphonates and urea derivatives to prove the wide scope of the process. As a novel by-product of the Biginelli-type synthesis of 3,4-dihydropyrimidin-2(1H)-one-phosphonates, the 5-diethoxyphosphoryl-4-phenyl-6-styryl-3,4-dihydropyrimidin-2(1H)-one was also isolated and characterized. Our MW-assisted method made also possible the condensation of aliphatic aldehydes, diethyl (2-oxopropyl)phosphonate and urea, which reaction was previously reported to be impossible in the literature.

Diethyl [(4-{(9H-carbazol-9-yl)methyl}-1H-1,2,3-triazol-1-yl)(benzamido)methyl]phosphonate

The title compound, diethyl [(4-{(9H-carbazol-9-yl)methyl}-1H-1,2,3-triazol-1-yl)(benzamido)methyl]phosphonate, was synthesized with excellent yield and high regioselectivity through 1,3-dipolar cycloaddition reaction between the α-azido diethyl amino methylphosphonate and the heterocyclic alkyne, 9-(prop-2-yn-1-yl)-9H-carbazole. The cyclization reaction by “click chemistry” was carried out in a water/ethanol solvent mixture (50/50), in the presence of copper sulfate pentahydrate and catalytic sodium ascorbate. The characterization of the structure of the resulting 1,4-regioisomer was performed by 1D and 2D-NMR experiments, infrared spectroscopy, and elemental analysis.