Influence of 6 or 8-substitution on the antiviral activity of 3-phenethylthiomethylimidazo[1,2-a]pyridine against human cytomegalovirus (HCMV) and varicella-zoster virus (VZV)

Bis(pyridine)enaminone as a Precursor for the Synthesis of Bis(azoles) and Bis(azine) Utilizing Recent Economic Green Chemistry Technology: The Q-Tube System

We reported herein efficient economic high-pressure synthesis procedures for the synthesis of bis(azoles) and bis(azines) by utilizing the bis(enaminone) intermediate. Bis(enaminone) reacted with hydrazine hydrate, hydroxylamine hydrochloride, guanidine hydrochloride, urea, thiourea, and malononitrile to form the desired bis azines and bis azoles. A combination of elemental analyses and spectral data was used to confirm the structures of the products. Compared with conventional heating, the high-pressure Q-Tube method promotes reactions in a short period of time and provides high yields.

Imidazopyridine, a promising scaffold with potential medicinal applications and structural activity relationship (SAR): recent advances

Imidazopyridine scaffold has gained tremendous importance over the past few decades. Imidazopyridines have been expeditiously used for the rationale design and development of novel synthetic analogs for various therapeutic disorders. A wide variety of imidazopyridine derivatives have been developed as potential anti-cancer, anti-diabetic, anti-tubercular, anti-microbial, anti-viral, anti-inflammatory, central nervous system (CNS) agents besides other chemotherapeutic agents. Imidazopyridine heterocyclic system acts as a key pharmacophore motif for the identification and optimization of lead structures to increase medicinal chemistry toolbox. The present review highlights the medicinal significances of imidazopyridines for their rationale development as lead molecules with improved therapeutic efficacies. This review further emphasis on the structure-activity relationships (SARs) of the various designed imidazopyridines to establish a relationship between the key structural features versus the biological activities.Communicated by Ramaswamy H. Sarma.

Ultrasound-Assisted Iodination of Imidazo[1,2-α]pyridines Via C-H Functionalization Mediated by tert-Butyl Hydroperoxide

A novel metal catalyst-free and environmentally friendly method for the regioselective iodination of imidazo[1,2-α]pyridines at their C3 position is disclosed, which has a wide substrate scope and could be sustainable. This reaction proceeds through ultrasound acceleration in the presence of a green alcohol solvent. Compared with a conventional heating system, the reaction efficiency and the rate are significantly improved and the iodine atom economy is maximized using ultrasound techniques.

Structural characterization and Hirshfeld surface analysis of a CoII complex with imidazo[1,2-a]pyridine

A new mononuclear tetra-hedral CoII complex, di-chlorido-bis-(imidazo[1,2-a]pyridine-κN1)cobalt(II), [CoCl2(C7H6N2)2], has been synthesized using a bioactive imidazo-pyridine ligand. X-ray crystallography reveals that the solid-state structure of the title complex exhibits both C-H⋯Cl and π-π stacking inter-actions in building supra-molecular assemblies. Indeed, the mol-ecules are linked by C-H⋯Cl inter-actions into a two-dimensional framework, with finite zero-dimensional dimeric units as building blocks, whereas π-π stacking plays a crucial role in building a supra-molecular layered network. An exhaustive investigation of the diverse inter-molecular inter-actions via Hirshfeld surface analysis enables contributions to the crystal packing of the title complex to be qu-anti-fied. The fingerprint plots associated with the Hirshfeld surface clearly display each significant inter-action involved in the structure, by qu-anti-fying them in an effective visual manner.

Synthesis, anti-varicella-zoster virus and anti-cytomegalovirus activity of quinazoline-2,4-diones containing isoxazolidine and phosphonate substructures

Cycloadditions of N-substituted C-(diethoxyphosphoryl)nitrones to N-allylated quinazoline-2,4-diones functionalized at N3 with substituted benzoyl or benzyl groups proceeded with moderate to good diastereoselectivities (d.e. 28-68%). The synthesized isoxazolidine phosphonates were assessed for the antiviral activity against a broad range of DNA and RNA viruses. Compounds trans-13c, cis-13c/trans-13c (86:14), cis-15b/trans-15b (87:13) and trans-15d/cis-15d (95:5) exhibited the highest activity toward both TK⁺ and TK^- VZV strains (mean EC₅₀ values in the range of 3.0-8.7 μM). The EC₅₀'s for isoxazolidines trans-12a, cis-12a, cis-13a, trans-13d, cis-15a/trans-15a (50:50) ranged between 6.9 and 8.5 μM for VZV TK⁺ strain and between 10.7 and 13.2 μM for VZV TK^- strain. The isoxazolidine phosphonates cis-15/trans-15 having benzyl substituents both at N3 of the quinazoline-2,4-dione skeleton and at N2 of the isoxazolidine ring displayed some anti-cytomegalovirus potency but at the same time showed significant cytostatic activity for human embryonic lung fibroblasts (used to carry out the antiviral assays) as well as for other cell lines (i.e. CEM, L1210, HeLa and HMEC-1).

A small-molecule cell-based screen led to the identification of biphenylimidazoazines with highly potent and broad-spectrum anti-apicomplexan activity

An in vitro screening of the anti-apicomplexan activity of 51 compounds, stemming from our chemical library and from chemical synthesis, was performed. As a study model, we used Toxoplasma gondii (T. gondii), expressing β-galactosidase for the colorimetric assessment of drug activity on parasites cultivated in vitro. This approach allowed the validation of a new series of molecules with a biphenylimidazoazine scaffold as inhibitors of T. gondii growth in vitro. Hence, 8 molecules significantly inhibited intracellular replication of T. gondii in vitro, with EC50 < 1 μM, while being non-toxic for human fibroblasts at these concentrations. Most attractive candidates were then selected for further biological investigations on other apicomplexan parasites (Neospora caninum, Besnoitia besnoiti, Eimeria tenella and Plasmodium falciparum). Finally, two compounds were able to inhibit growth of four different apicomplexans with EC50 in the submicromolar to nanomolar range, for each parasite. These data, including the broad anti-parasite spectrum of these inhibitors, define a new generation of potential anti-parasite compounds of wide interest, including for veterinary application. Studies realized on E. tenella suggest that these molecules act during the intracellular development steps of the parasite. Further experiments should be done to identify the molecular target(s) of these compounds.

Synthesis and anti-HCMV activity of 1-[ω-(phenoxy)alkyl]uracil derivatives and analogues thereof

HCMV infection represents a life-threatening condition for immunocompromised patients and newborn infants and novel anti-HCMV agents are clearly needed. In this regard, a series of 1-[ω-(phenoxy)alkyl]uracil derivatives were synthesized and examined for antiviral properties. Compounds 17, 20, 24 and 28 were found to exhibit highly specific and promising inhibitory activity against HCMV replication in HEL cell cultures with EC50 values within 5.5-12μM range. Further studies should be undertaken to elucidate the mechanism of action of these compounds and the structure-activity relationship for the linker region.

One-pot synthesis of 2-phenylimidazo[1,2-α]pyridines from acetophenone, [Bmim]Br(3) and 2-aminopyridine under solvent-free conditions

One-pot synthesis of 2-phenylimidazo[1,2-α]pyridines from acetophenone, [Bmim]Br₃ and 2-aminopyridine under solvent-free conditions in the presence of Na₂CO₃, gave the corresponding 2-phenylimidazo[1,2-α]pyridines in excellent yields ranging from 72% to 89%.

Influence of 6- or 8-substitution on the antiviral activity of 3-arylalkylthiomethylimidazo[1,2-a]pyridine against human cytomegalovirus (CMV) and varicella-zoster virus (VZV): part II

The synthesis of original imidazo[1,2-a]pyridines bearing a thioether side chain at the 3 position and diversely substituted on the 6 or 8 position, and their antiviral activities are reported. From the synthesized compounds, the imidazo[1,2-a]pyridines bearing a 5 membered heterocycle (thiophene, furane or pyrrole) in the 6 position or a phenylthio group in the 6 or 8 position were the most potent against human cytomegalovirus (CMV) and varicella-zoster virus (VZV), whereas several other congeners, while less potent, were more selective in their inhibitory activity against VZV and CMV. These compounds showed similar activity against thymidine kinase competent (TK+) and deficient (TK-) VZV strains, demonstrating a mechanism of action independent of the viral thymidine kinase.