Copper Acetate Catalyzed Regio­selective Synthesis of Substituted 1,2,3-Triazoles: A Versatile Azide-Alk­ene Cycloaddition/Oxidation Approach

Palladium-Catalyzed Tandem Reactions via Allene Intermediates for the Rapid Synthesis of a Fused Indenone-Indole Scaffold

A palladium-catalyzed tandem reaction of 1-(2-iodophenyl)-3-arylprop-2-yn-1-ones and 1-(2-azidophenyl)propargyl ethers is developed to provide the rapid construction of a fused polycyclic indenone-indole scaffold under mild conditions. The reaction proceeds via a highly ordered process involving Sonogashira coupling, propargyl-allenyl isomerization, allene-azide cycloaddition, denitrogenation, and diradical coupling. The proposed reaction mechanism is supported by experimental and computational studies.

Chemistry-led investigations into the mode of action of NAMPT activators, resulting in the discovery of non-pyridyl class NAMPT activators

The cofactor nicotinamide adenine dinucleotide (NAD⁺) plays a key role in a wide range of physiological processes and maintaining or enhancing NAD⁺ levels is an established approach to enhancing healthy aging. Recently, several classes of nicotinamide phosphoribosyl transferase (NAMPT) activators have been shown to increase NAD⁺ levels in vitro and in vivo and to demonstrate beneficial effects in animal models. The best validated of these compounds are structurally related to known urea-type NAMPT inhibitors, however the basis for the switch from inhibitory activity to activation is not well understood. Here we report an evaluation of the structure activity relationships of NAMPT activators by designing, synthesising and testing compounds from other NAMPT ligand chemotypes and mimetics of putative phosphoribosylated adducts of known activators. The results of these studies led us to hypothesise that these activators act via a through-water interaction in the NAMPT active site, resulting in the design of the first known urea-class NAMPT activator that does not utilise a pyridine-like warhead, which shows similar or greater activity as a NAMPT activator in biochemical and cellular assays relative to known analogues.

Synthesis of fully functionalized spirostanic 1,2,3-triazoles by the three component reaction of diosgenin azides with acetophenones and aryl aldehydes and their biological evaluation as antiproliferative agents

Diosgenin is of significant interest due to its biological activity and synthetic application. In this study, we report the synthesis of a series of spirostanic 1,4,5-trisubstituted 1,2,3-triazoles by the three component reaction of (25R)-6-azidospirostan-3,5-diols with acetophenones and aryl aldehydes. The one-pot two step synthesis proceeds through the in situ formation of (E)-chalcones and copper catalyzed reaction with organic azides in DMF medium. Structural diversity was achieved by varying the aldehyde and acetophenone nature as well as the spirostanic azide stereochemistry. The results of in vitro biological assays showed that fully decorated spirostanic 1,2,3-triazoles exerted significant and selective antiproliferative activity against MCF-7, glioblastoma (SNB-19, T98G, A-172) and neuroblastoma (IMR-32, SH-SYSY) (HCT116) cell lines (GI₅₀ in the single-digit micromolar range). The data revealed that benzoyl and aryl substitutions in the triazole ring introduced at the 6β-position significantly improved the anti-tumor activity of (25R)-6-azidospirostan-3β,5α-diols. This position on the spirostan core may be the favourable to synthesize of potent anticancer leads from diosgenin.

Copper-Promoted One-Pot Sandmeyer-Type Reaction for the Synthesis of N-Aryltriazoles

Herein, we report the copper-catalyzed one-pot Sandmeyer-type reaction of aromatic amines with triazoles to afford N-aryl-1,2,3-triazoles. Diazonium salts, formed from aromatic amines and tert-butyl nitrite in the presence of fluoroboric acid, reacted with triazoles in a copper-catalyzed Sandmeyer-type reaction. The reaction proceeded under mild conditions to afford N-aryltriazoles in moderate to good yields. This method is amenable to a wide range of aromatic amines and triazoles and shows diverse functional group tolerance. Inhibition of the reaction upon the addition of free radical scavengers suggested a radical pathway, in which the aryl radical, copper, and triazole formed a complex that underwent reductive elimination to give aryltriazole compounds; this is consistent with the mechanism underlying the Sandmeyer reaction. Thus, we demonstrate a new effective strategy for the construction of C-N bonds via Sandmeyer-type reactions and a valuable alternative approach for the synthesis of aryltriazole derivatives.

Synthesis, biological evaluation and molecular docking studies of novel 1,2,3-triazole-quinazolines as antiproliferative agents displaying ERK inhibitory activity

ERK1/2 inhibitors have attracted special attention concerning the ability of circumventing cases of innate or log-term acquired resistance to RAF and MEK kinase inhibitors. Based on the 4-aminoquinazoline pharmacophore of kinases, herein we describe the synthesis of 4-aminoquinazoline derivatives bearing a 1,2,3-triazole stable core to bridge different aromatic and heterocyclic rings using copper-catalysed azide-alkyne cycloaddition reaction (CuAAC) as a Click Chemistry strategy. The initial screening of twelve derivatives in tumoral cells (CAL-27, HN13, HGC-27, and BT-20) revealed that the most active in BT-20 cells (25a, IC₅₀ 24.6 μM and a SI of 3.25) contains a more polar side chain (sulfone). Furthermore, compound 25a promoted a significant release of lactate dehydrogenase (LDH), suggesting the induction of cell death by necrosis. In addition, this compound induced G0/G1 stalling in BT-20 cells, which was accompanied by a decrease in the S phase. Western blot analysis of the levels of p-STAT3, p-ERK, PARP, p53 and cleaved caspase-3 revealed p-ERK1/2 and p-STA3 were drastically decreased in BT-20 cells under 25a incubation, suggesting the involvement of these two kinases in the mechanisms underlying 25a-induced cell cycle arrest, besides loss of proliferation and viability of the breast cancer cell. Molecular docking simulations using the ERK-ulixertinib crystallographic complex showed compound 25a could potentially compete with ATP for binding to ERK in a slightly higher affinity than the reference ERK1/2 inhibitor. Further in silico analyses showed comparable toxicity and pharmacokinetic profiles for compound 25a in relation to ulixertinib.

Tetraamminecopper(II) Sulfate Monohydrate in Oxidative Azide-olefin Cyclo-addition and Three-component Click Reaction

INTRODUCTION

An effective Cu-complex, [Cu(NH3)4SO4 • H2O] was prepared conveniently from the inexpensive and easily available starting reagents in a simple route.

MATERIALS AND METHODS

Excellent reactivity of the catalyst was observed towards two competent clickcycloadditions: (a) oxidative cycloaddition of azides with electron-poor olefins and (b) one-pot cycloaddition of alkynes with boronic acid and sodium azide under "click-appropriate" conditions.

RESULTS

No external oxidant, short reaction time, high product yield, wide substrate scope, and aqueous solvent media make the azide-olefin cycloaddition approach a greener route in contrast to the reported methods.

CONCLUSION

The newly developed mild, green, and rapid three-component strategy shows product diversity with superb yields at room temperature by reducing the synthetic process time and using only 1 mol % of the synthesized copper complex.

Catalyst-free facile synthesis of polycyclic indole/pyrrole substituted-1,2,3-triazoles

A general and catalyst-free access to the fused polycyclic N-heterocycles via an intramolecular azide-alkene cascade reaction under mild reaction conditions has been developed. The reaction is applicable to both indole and pyrrole substrates, and a variety of substituents are tolerated. The entire sequence can be carried out in a one-pot operation. This methodology provides a sustainable and efficient access to a variety of novel polycyclic indole/pyrrole substituted-1,2,3-triazoles.

Regioselective Synthesis of N2-Alkylated-1,2,3 Triazoles and N1-Alkylated Benzotriazoles: Cu2S as a Recyclable Nanocatalyst for Oxidative Amination of N, N-Dimethylbenzylamines

Copper chalcogenide nanoparticles (Cu₂S) synthesized for the first time from a single-source precursor, CuSPh, act as highly efficient and reusable heterogeneous catalyst for regioselective amination of N, N-dimethylbenzylamines with various azoles. The reaction involves N-H/C-H cross-dehydrogenative coupling (CDC) and demonstrates wide functional group tolerance. It provides highly selective access to N¹-alkylated benzotriazoles, N²-alkylated 1,2,3-triazoles and 4-phenyl-1,2,3-triazoles, and N-alkylated carbazoles in 70-89% yields under solvent-free conditions. The Cu₂S nanocatalyst has been characterized by PXRD, XPS, SEM-EDX, and HR-TEM analysis. Mechanistic studies suggest that the reaction follows a radical pathway and involves an iminium ion intermediate.

Copper-Catalyzed Cross-Dehydrogenative N2-Coupling of NH-1,2,3-Triazoles with N,N -Dialkylamides: N-Amidoalkylation of NH-1,2,3-Triazoles

An efficient copper-catalyzed C-N bond formation by N-H/C-H cross-dehydrogenative coupling (CDC) between NH-1,2,3-triazoles and N,N-dialkylamides has been developed. The method provided N-amidoalkylated 1,2,3-triazoles with moderate to high yields, and the reactions showed high N²-selectivities when 4,5-disubstituted NH-1,2,3-triazoles served as the substrates.