Benzylic Aroylation of Toluenes Mediated by a LiN(SiMe3)2/Cs+ System

Chemoselective deprotonative functionalization of benzylic C-H bonds is challenging, because the arene ring contains multiple aromatic C(sp²)-H bonds, which can be competitively deprotonated and lead to selectivity issues. Recently it was found that bimetallic [MN(SiMe₃)₂ M = Li, Na]/Cs⁺ combinations exhibit excellent benzylic selectivity. Herein, is reported the first deprotonative addition of toluenes to Weinreb amides mediated by LiN(SiMe₃)₂/CsF for the synthesis of a diverse array of 2-arylacetophenones. Surprisingly, simple methyl benzoates also react with toluenes under similar conditions to form 2-arylacetophenones without double addition to give tertiary alcohol products. This finding greatly increases the practicality and impact of this chemistry. Some challenging substrates with respect to benzylic deprotonations, such as fluoro and methoxy substituted toluenes, are selectively transformed to 2-aryl acetophenones. The value of benzylic deprotonation of 3-fluorotoluene is demonstrated by the synthesis of a key intermediate in the preparation of Polmacoxib.

Recent developments in the synthesis of azaindoles from pyridine and pyrrole building blocks

The azaindole framework is ubiquitous in bioactive natural products and pharmaceuticals. This review highlights the synthetic approaches to azaindoles with advantages and limitations, mechanistic pathways and biological importance.

The importance of indole and azaindole scaffold in the development of antitumor agents

With some indoles and azaindoles being successfully developed as anticancer drugs, the design and synthesis of indole and azaindole derivatives with remarkable antitumor activity has received increasing attention and significant progress has been made. This paper reviews the recent progress in the study of tumorigenesis, mechanism of actions and structure activity relationships about anticancer indole and azindole derivatives. Combining structure activity relationships and molecular targets-related knowledge, this review will help researchers design more effective, safe and cost-effective anticancer indoles and azindoles agents.

Palladium-Catalyzed Direct α-C(sp3) Heteroarylation of Ketones under Microwave Irradiation

Heteroaryl compounds are valuable building blocks in medicinal chemistry and chemical industry. A palladium-catalyzed direct α-C(sp3) heteroarylation of ketones under microwave irradiation is developed and reported in this study. Under optimized conditions, twenty-eight (28) heteroarylated ketones were prepared in this study to demonstrate the substrate scope of this reaction. The ground-state optimized structure of Pd(0) active catalyst with 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl (XPhos) in toluene, and the products of its reaction with 3-bromopyridine and acetophenone were studied using all-atom density functional theory. This study provided insightful information for palladium catalytic system design to generate heteroaryl compounds.

DYRK1A kinase inhibition with emphasis on neurodegeneration: A comprehensive evolution story-cum-perspective

Alzheimer, the fourth leading cause of death embodies a key responsible event including formation of β-amyloid protein clustering to amyloid plaque on blood vessels. The origin of above events is Amyloid precursor protein (APP) which is an integral membrane protein known for its function in synapses formation. Modern research had proposed that the over expression of DYRK1A (Dual specificity tyrosine phosphorylation regulated kinase1A, a family of protein kinases, positioned within the Down's syndrome critical region (DSCR) on human chromosome 21causes phosphorylation of APP protein resulting in its cleavage to Aβ 40, 42 and tau proteins (regulated by beta and gamma secretase) which plays critical role in early onset of Alzheimer's disease (AD) detected in Down's syndrome (DS), leading to permanent functional and structural deformities which results ultimately into neuro-degeneration and neuronal death. Therefore, DYRK1A emerges as a potential target for prevention of neuro-degeneration and hence Alzheimer. Presently, the treatment methods for Down's syndrome, as well as Alzheimer's disease are extremely biased and represent a major deficiency for therapeutic necessities. We hereby, focus our review on the current status of the research and contributions in the development of DYRK1A inhibitors.

Understanding and Interrupting the Fischer Azaindolization Reaction

Experimental and computational studies pertaining to the Fischer azaindolization reaction are reported. These studies explain why pyridylhydrazines are poorly reactive in Fischer indolization reactions, in addition to the origin of hydrazine substituent effects. Additionally, an interrupted variant of Fischer azaindolization methodology is disclosed, which provides a synthetic entryway into fused azaindoline scaffolds.

Azaindole synthesis through dual activation catalysis with N-heterocyclic carbenes

A convergent, transition-metal-free synthesis of 2-aryl-azaindoles has been developed. The interception of a reactive aza-ortho-azaquinone methide intermediate by an acyl anion equivalent generated through carbene catalysis provides high yields, a wide substrate scope, and the synthesis of previously inaccessible azaindoles.

Decorated 6,6′,7,7′-tetrahydro-1H,1′H-2,3′-biindole scaffold as promising candidate for recognition of the CDK2 allosteric site

Decorated 6,6′,7,7′-tetrahydro-1H,1′H-2,3′-biindoles, such as DPIT, targeting CDK2 seem to be an attractive scaffold for development of useful anticancer drugs.

The azaindole framework in the design of kinase inhibitors

This review article illustrates the growing use of azaindole derivatives as kinase inhibitors and their contribution to drug discovery and innovation. The different protein kinases which have served as targets and the known molecules which have emerged from medicinal chemistry and Fragment-Based Drug Discovery (FBDD) programs are presented. The various synthetic routes used to access these compounds and the chemical pathways leading to their synthesis are also discussed. An analysis of their mode of binding based on X-ray crystallography data gives structural insights for the design of more potent and selective inhibitors.

Synthesis and optimization of an original V-shaped collection of 4-7-disubstituted pyrido[3,2-d]pyrimidines as CDK5 and DYRK1A inhibitors

We here report the synthesis and biological evaluation of an original collection of 4,7-disubstituted pyrido[3,2-d]pyrimidines designed as potential kinase inhibitors. The collection was generated from a single starting material, 4,7-dichloropyrido[3,2-d]pyrimidine, which afforded the final compounds after two steps: a sequential or one-pot sequence including selective cross coupling reactions in C-4, followed by the second cross-coupling in C-7. In position C-4, a Suzuki-Miyaura type reaction led to monosubstituted derivatives whereas in position C-7, synthesis was achieved via a Suzuki or a Buchwald type reaction using commercially available or undescribed boron derivatives. The biological activity of the V-shaped family was measured in protein kinase assays. The structure activity relationship (SAR) revealed that some compounds selectively inhibited DYRK1A and CDK5 without affecting GSK3. Docking studies furnished possible explanations that correlate with the SAR data. The most active compound on the two biological targets was 27 which exhibited the following IC50: 110 nM for CDK5, 24 nM for DYRK1A and only 1.2 μM for GSK3. In the C-7 amino subfamily, the best derivative was indubitably compound 48 which led to a near selective action on DYRK1A and a remarkable IC50 of 60 nM.

Design and synthesis of a library of lead-like 2,4-bisheterocyclic substituted thiophenes as selective Dyrk/Clk inhibitors

The Dyrk family of protein kinases is implicated in the pathogenesis of several diseases, including cancer and neurodegeneration. Pharmacological inhibitors were mainly described for Dyrk1A so far, but in fewer cases for Dyrk1B, Dyrk2 or other isoforms. Herein, we report the development and optimization of 2,4-bisheterocyclic substituted thiophenes as a novel class of Dyrk inhibitors. The optimized hit compounds displayed favorable pharmacokinetic properties and high ligand efficiencies, and inhibited Dyrk1B in intact cells. In a larger selectivity screen, only Clk1 and Clk4 were identified as additional targets of compound 48, but no other kinases frequently reported as off-targets. Interestingly, Dyrk1A is implicated in the regulation of alternative splicing, a function shared with Clk1/Clk4; thus, some of the dual inhibitors might be useful as efficient splicing modulators. A further compound (29) inhibited Dyrk1A and 1B with an IC50 of 130 nM, showing a moderate selectivity over Dyrk2. Since penetration of the central nervous system (CNS) seems possible based on the physicochemical properties, this compound might serve as a lead for the development of potential therapeutic agents against glioblastoma. Furthermore, an inhibitor selective for Dyrk2 (24) was also identified, which might be are suitable as a pharmacological tool to dissect Dyrk2 isoform-mediated functions.