Synthesis and structure–activity relationship of imidazo[1,2-a]benzimidazoles as corticotropin-releasing factor 1 receptor antagonists

I2-DMSO-Mediated Construction of 2,3- and 2,4-Disubstituted Pyrimido[1,2-b]indazole Skeletons

An efficient synthetic method for constructing 2,3- and 2,4-disubstituted pyrimidio[1,2-b]indazole skeletons through I2-DMSO-mediated and substrate-controlled regioselective [4 + 2] cyclization is reported. The reaction conditions are mild, its operation is simple, and the substrate scope is wide. More than 60 pyrimidio[1,2-b]indazole derivatives have been synthesized, providing a new methodology for constructing related molecules and potentially enriching bioactive-molecule libraries.

Molecular iodine-promoted oxidative cyclization for the synthesis of 1,3,4-thiadiazole-fused- [1,2,4]-thiadiazole incorporating 1,4-benzodioxine moiety as potent inhibitors of α-amylase and α-glucosidase: In vitro and in silico study

Twenty-five analogs were synthesized based on 1,3,4-thiadiazole-fused-[1,2,4]-thiadiazole incorporating 1,4-benzodioxine moiety (1-25) and then tested for the antidiabetic profile. The entire afforded derivatives showed varied inhibition profiles ranging between 0.70 ± 0.01 and 30.80 ± 0.80 μM (against α-amylase) in comparison to standard acarbose (12.80 ± 0.10 μM). Similarly, synthetics analogs also displayed a varied range of α-glucosidase activity ranging from 0.80 ± 0.01 μM to IC50 = 29.70 ± 0.40 μM (against α-glucosidase) as compared to standard acarbose (IC50 = 12.90 ± 0.10 μM). Among synthesized analogs, compound 22 showed excellent potency due to the presence of di-hydroxy substitutions at the 2,3-position of the aryl ring. For all analogs, the structure-activity relationship was carried out based on the pattern of substitutions around the aryl ring, and further, the potent analogs were subjected to a molecular docking study to analyze how active residues of targeted enzymes interact with active parts of newly prepared analogs. The result obtained shows that these compounds furnish several key interactions with enzyme active sites and, hence, enhanced their enzymatic activities.

Controllable Site-Selective Construction of 2- and 4-Substituted Pyrimido[1,2-b]indazole from 3-Aminoindazoles and Ynals

A straightforward and novel controllable site-selective construction of 2- and 4-substituted pyrimido[1,2-b]indazole from 3-aminoindazoles and ynals has been developed. The high regioselectivity of this reaction could be easily switched by converting different catalytic systems. In this way, a series of 2- and 4-substituted pyrimido[1,2-b]indazole derivatives were obtained in moderate to good yields. In addition, the photophysical properties of compound 3a prepared by the present method were discussed.

Molecular Iodine-Promoted [3 + 2] Oxidative Cyclization for the Synthesis of Heteroarene-Fused [1,2,4] Thiadiazoles/Selenadiazoles

Two new classes of heteroarene-fused [1,2,4]thiadiazole and [1,2,4]selenadiazole are synthesized through the iodine-mediated [3 + 2] oxidative cyclization of 2-aminoheteroarenes and isothiocyanates/isoselenocyanates. This oxidative [3 + 2] annulation strategy is highly regiospecific to proceed a selective C-N bond formation at the endo-nitrogen of 2-aminoheteroarenes followed by an intramolecular oxidative N-S/N-Se bond formation. It is the first example of an I₂-mediated oxidative nitrogen-selenium (N-Se) bond formation.

An approach towards the synthesis of novel fused nitrogen tricyclic heterocyclic scaffolds via GBB reaction

A concise and efficient one-pot synthesis of novel N-fused tricyclic derivatives has been developed by using the Groebke–Blackburn–Bienaymé (GBB) reaction, which involved the reaction of 3-amino-1H-indazoles, aldehydes and isonitriles to afford 2-aryl-5H-imidazo[1,2-b]indazol-3-amine derivatives via a formal [4 + 1] cycloaddition reaction.

Copper catalyzed aerobic oxidative cyclization and ketonization: one pot synthesis of benzoimidazo[1,2-a]imidazolones

A highly efficient synthesis of benzoimidazo[1,2-a]imidazolone through a novel oxidative 5-exo-dig cyclization-ketonization cascade of 2-aminobenzimidazole, aldehyde and terminal alkyne has been explored under aerobic conditions.

Recent Trends in Copper-Catalyzed C-H Amination Routes to Biologically Important Nitrogen Scaffolds

Nitrogen-containing heterocycles have found remarkable applications in natural product research, material sciences, and pharmaceuticals. Although the synthesis of this interesting class of compounds attracted the interest of generations of organic chemists, simple and straightforward assembly methods based on transition-metal catalysis have regularly been elusive. The recent advancements in the development of C-H functionalization have helped in accomplishing the synthesis of a variety of complex heterocycles from simple precursors. This Focus Review summarizes the recent advances in one particular field: the copper-catalyzed C-N bond formation reactions via C-H bond functionalization to furnish a comprehensive range of nitrogen heterocycles. Applicability and synthetic feasibility of a particular reaction represent major requirements for the inclusion in this review.

Medicinal applications of perfluoroalkylated chain-containing compounds

Compounds with polyfluorinated molecular fragments possess unique properties associated with the presence of a large number of fluorine atoms that affect lipophilicity and conformational rigidity of the parent molecule along with other effects. The aim of this review is to provide an overview of synthesized compounds possessing perfluoroalkylated or polyfluorinated chains that have been tested for bioactivity or as potential drug candidates for the treatment of various diseases. As far as the length of the perfluoroalkylated chain is concerned the focus is centered on the compound bearing perfluoroethyl or tetrafluoroethyl as well as longer chains. The perfluoroalkylated compounds discussed are classified according to their biological activity.

One-pot, two-step synthesis of imidazo[1,2-a]benzimidazoles via a multicomponent [4 + 1] cycloaddition reaction

A one-pot, two-step synthesis of imidazo[1,2-a]benzimidazoles has been achieved by a three-component reaction of 2-aminobenzimidazoles with an aromatic aldehyde and an isocyanide. The reaction involving condensation of 2-aminobenzimidazole with an aldehyde is run under microwave activation to generate an imine intermediate under basic conditions which then undergoes [4 + 1] cycloaddition with an isocyanide.

Pharmacophore Modelling and 3D-QSAR Studies on N(3)-Phenylpyrazinones as Corticotropin-Releasing Factor 1 Receptor Antagonists

Pharmacophore modelling-based virtual screening of compound is a ligand-based approach and is useful when the 3D structure of target is not available but a few known active compounds are known. Pharmacophore mapping studies were undertaken for a set of 50 N(3)-phenylpyrazinones possessing Corticotropin-releasing Factor 1 (CRF 1) antagonistic activity. Six point pharmacophores with two hydrogen bond acceptors, one hydrogen bond donor, two hydrophobic regions, and one aromatic ring as pharmacophoric features were developed. Amongst them the pharmacophore hypothesis AADHHR.47 yielded a statistically significant 3D-QSAR model with 0.803 as R (2) value and was considered to be the best pharmacophore hypothesis. The developed pharmacophore model was externally validated by predicting the activity of test set molecules. The squared predictive correlation coefficient of 0.91 was observed between experimental and predicted activity values of test set molecules. The geometry and features of pharmacophore were expected to be useful for the design of selective CRF 1 receptor antagonists.

Microwave promoted simple, efficient and regioselective synthesis of trisubstituted imidazo[1,2-a]benzimidazoles on soluble support

An efficient microwave-assisted and soluble polymer-supported synthesis of medicinally important imidazole-fused benzimidazoles has been developed. The protocol involves the rapid condensation of polymer-bound amino benzimidazoles with various α-bromoketones and subsequent in situ intramolecular cyclization under microwave irradiation resulting in a one pot synthesis of imidazole interlacing benzimidazole polymer conjugates. The condensed product was obtained with excellent regioselectivity. The biologically interesting imidazo[1,2-a]benzimidazoles was released from polymer support at ambient temperature. Diversity in the triheterocyclic nucleus was achieved by the different substitutions at its 2, 3, and 9 positions. The new protocol has the advantages of short reaction time, easy workup process, excellent yields, reduced environmental impact, wide substrate scope and convenient procedure.

Corticotropin-releasing factor receptor antagonists

Corticotropin-releasing factor (CRF) coordinates the neural, endocrine and immune responses of the body to stress. Therefore, CRF receptors are important targets for the design of drugs for depression, anxiety and stress-related disorders. Several laboratories have published extensive preclinical and limited clinical research into the role of CRF in human disease. This review covers developments in the patent literature during 2002 - 2006 and outlines the prospects for CRF-based therapy for mental illness.

Progress in corticotropin-releasing factor-1 antagonist development

Corticotropin releasing factor (CRF) receptor antagonists have been sought since the stress-secreted peptide was isolated in 1981. Although evidence is mixed concerning the efficacy of CRF(1) antagonists as antidepressants, CRF(1) antagonists might be novel pharmacotherapies for anxiety and addiction. Progress in understanding the two-domain model of ligand-receptor interactions for CRF family receptors might yield chemically novel CRF(1) receptor antagonists, including peptide CRF(1) antagonists, antagonists with signal transduction selectivity and nonpeptide CRF(1) antagonists that act via the extracellular (rather than transmembrane) domains. Novel ligands that conform to the prevalent pharmacophore and exhibit drug-like pharmacokinetic properties have been identified. The therapeutic utility of CRF(1) antagonists should soon be clearer: several small molecules are currently in Phase II/III clinical trials for depression, anxiety and irritable bowel syndrome.

One-pot Regioselective Synthesis of 2,9-Disubstituted Imidazo[1,2-a] Benzimidazoles from 2-Aminobenzimidazole and α-Tosyloxy Ketones

One-pot regioselective synthesis in high yields of 2,9-disubstituted imidazo[1,2-a]benzimidazoles from 2-aminobenzimidazole and α-tosyloxy ketones is described.

An orally active corticotropin releasing factor 1 receptor antagonist from 8-aryl-1,3a,7,8-tetraaza-cyclopenta[a]indenes

8-Aryl-1,3a,7,8-tetraaza-cyclopenta[a]indenes represent a novel series of high-affinity corticotropin-releasing factor-1 receptor (CRF1R) antagonists. Herein we report the synthesis and SAR around the tricyclic core and the anxiolytic activity of an orally dosed exemplary compound 9d (K(i)=8.0 nM) in a mouse canopy model.