Catalyst-controlled directing group translocation in the site selective C-H functionalization of 3-carboxamide indoles and metallocarbenes

Complementary methods toward the selective functionalization of indole and oxindole frameworks employing an alternative strategy in heteroaryl C-H functionalizations are presented herein. This work focuses on a catalyst-controlled, site selective C-H activation/functionalization of 3-acyl indoles, wherein an amide serves as a robust and versatile directing group capable of undergoing concomitant 1,2-acyl translocation/C-H functionalization in the presence of a RhI/AgI co-catalysts to provide the cross-coupled adducts in high yields. In contrast, the use of IrIII/AgI catalysts subverted the 1,2-acyl migration to afford the corresponding C2-functionalized products in good to excellent yields. A notable feature of the catalyst systems was the exceptional level of site selectivity observed in which the corresponding C-H functionalized indoles were obtained exclusively. Mechanistic experiments indicate a concerted 1,2-acyl migration step and indole metallation occurring through an electrophilic aromatic substitution process.

Antineoplastic indole-containing compounds with potential VEGFR inhibitory properties

Cancer is one of the most significant health challenges worldwide. Various techniques, tools and therapeutics/materials have been developed in the last few decades for the treatment of cancer, together with great interest, funding and efforts from the scientific society. However, all the reported studies and efforts seem insufficient to combat the various types of cancer, especially the advanced ones. The overexpression of tyrosine kinases is associated with cancer proliferation and/or metastasis. VEGF, an important category of tyrosine kinases, and its receptors (VEGFR) are hyper-activated in different cancers. Accordingly, they are known as important factors in the angiogenesis of different tumors and are considered in the development of effective therapeutic approaches for controlling many types of cancer. In this case, targeted therapeutic approaches are preferable to the traditional non-selective approaches to minimize the side effects and drawbacks associated with treatment. Several indole-containing compounds have been identified as effective agents against VEGFR. Herein, we present a summary of the recent indolyl analogs reported within the last decade (2012-2023) with potential antineoplastic and VEGFR inhibitory properties. The most important drugs, natural products, synthesized potent compounds and promising hits/leads are highlighted. Indoles functionalized and conjugated with various heterocycles beside spiroindoles are also considered.

Synthetic Methodologies and Therapeutic Potential of Indole-3-Carbinol (I3C) and Its Derivatives

Indole-3-carbinol (I3C) is a natural product contained in vegetables belonging to the Brassicaceae family and has been studied in recent decades for its biological and pharmacological properties. Herein, we will analyze: (1) the biosynthetic processes and synthetic procedures through which I3C and its main derivatives have been obtained; (2) the characteristics that lead to believe that both I3C and its derivatives are responsible for several important activities-in particular, antitumor and antiviral, through insights concerning in vitro assays and in vivo tests; (3) the mechanisms of action of the most important compounds considered; (4) the potential social impact that the enhancement of the discussed molecules can have in the prevention and treatment of the pathologies' examined field-first of all, those related to respiratory tract disorders and cancer.

Directed C-H Functionalization of C3-Aldehyde, Ketone, and Acid/Ester-Substituted Free (NH) Indoles with Iodoarenes via a Palladium Catalyst System

Pd(II)-catalyzed C-H arylations of free (NH) indoles including different carbonyl directing groups on C3-position with aryl iodides are demonstrated. Importantly, the reactions are carried out using the same catalyst system without any additional transient directing group (TDG). In this study, the formyl group as a directing group gave the C4-arylated indoles versus C2-arylation. Using this catalyst system, C-H functionalization of 3-acetylindoles provided domino C4-arylation/3,2-carbonyl migration products. This transformation involves the unusual migration of the acetyl group to the C2-position following C4-arylation in one pot. Meanwhile, migration of the acetyl group could be simply controlled and N-protected 3-acetylindoles afforded C4-arylation products without migration of the acetyl group. Functionalization of indole-3-carboxylic acid (or methyl ester) with aryl iodides using the present Pd(II)-catalyst system resulted in decarboxylation followed by the formation of C2-arylated indoles. Based on the control experiments and the literature, plausible mechanisms are proposed. The synthetic utilities of these acetylindole derivatives have also been demonstrated. Remarkably, C4-arylated acetylindoles have allowed the construction of functionalized pityiacitrin (a natural product).

Advances in 2-substituted benzothiazole scaffold-based chemotherapeutic agents

Targeted therapy plays a pivotal role in cancer therapeutics by countering the drawbacks of conventional treatment like adverse events and drug resistance. Over the last decade, heterocyclic derivatives have received considerable attention as cytotoxic agents by modulating various signaling pathways. Benzothiazole is an important heterocyclic scaffold that has been explored for its therapeutic potential. Benzothiazole-based derivatives have emerged as potent inhibitors of enzymes such as EGFR, VEGFR, PI3K, topoisomerases, and thymidylate kinases. Several researchers have designed, synthesized, and evaluated benzothiazole scaffold-based enzyme inhibitors. Of these, several inhibitors have entered various phases of clinical trials. This review describes the recent advances and developments of benzothiazole architecture-based derivatives as potent anticancer agents.

Synthesis and evaluation of in vitro cytotoxic effects of triazol/spiroindolinequinazolinedione, triazol/indolin-3-thiosemicarbazone and triazol/thiazol-indolin-2-one conjugates

PURPOSE

Cancer as one of the major diseases with high mortality rates threats human life in the world. Subsequently, the design new potent anticancer agents has attracted much attention in the area of synthetic and medicinal chemistry. In this study, new triazol-linked spiroindolinequinazolinone, thiazol-oxindole and oxindole-thiosemicarbazone conjugates were synthesized and evaluated for their in vitro cytotoxic activity toward different cancer lines.

METHODS

Some new triazol-linked oxindoles and spirooxindoles conjugates were synthesized. The synthesized compounds were tested for their in vitro cytotoxic activity toward cancer lines including A375, PC3, LNCaP, MDA MB231 and normal cells HDF (human dermal fibroblast).

RESULTS

Among all synthesized compounds, the triazol-linked oxindol-thiosemicarbazone conjugate 10b showed the highest cytotoxic activity against different cancer cells. By using quantitative real time PCR (qRT-PCR), it was found that 10b is able to induce apoptosis by alteration of Bax, Bcl2 balance (i.e. by up regulation of Bax and down regulation of Bcl-2 mRNA expression levels). The DAPI staining was used to show the death of cancer cells in the presence of 10b. Interestingly, 10b suppressed the migration of LNCaP cancer cells by up-regulation of epithelial markers (E-cadherin) and down-regulation of mesenchymal markers (vimentin).

CONCLUSION

Our findings revealed that the compound 10b may be a new potent candidate with multiple biological activities to design therapeutic agents against different cancers. Synthesis and evaluation of in vitro cytotoxic effects of triazol/spiroindolinequinazolinedione, triazol/indolin-3-thiosemicarbazone and triazol/thiazol-indolin-2-one conjugates.

Design, synthesis, and antitumor activity of novel benzoheterocycle derivatives as inhibitors of vascular endothelial growth factor receptor-2 tyrosine kinase

The vascular endothelial growth factor receptor-2 signaling pathway promotes the formation of new blood vessels, and vascular endothelial growth factor receptor-2 tyrosine kinase exists in both active and inactive conformations. Novel indole–benzimidazole and indole–benzothiazole derivatives joined by different linkers are designed and synthesized as inhibitors of vascular endothelial growth factor receptor-2 tyrosine kinase. All the synthesized compounds were evaluated for their cytotoxicity against four human cancer cell lines (HeLa, HT29, A549, and MDA-MB-435) and human umbilical vein endothelial cell. Meanwhile, the inhibitory activities against vascular endothelial growth factor receptor-2 are estimated in vitro and the binding interactions with dual conformations of vascular endothelial growth factor receptor-2 tyrosine kinase are evaluated by molecular docking. Compounds 5a–c and 14 show inhibitory activity against vascular endothelial growth factor receptor-2 tyrosine kinase and promising cytotoxicity, specifically with IC50 values ranging between 0.1 and 1 μM, which imply broad-spectrum antitumor activity. These results provide a deep insight into potential structural modifications for developing potent vascular endothelial growth factor receptor-2 tyrosine kinase inhibitors.

The palladium-catalyzed direct C3-cyanation of indoles using acetonitrile as the cyanide source

The palladium-catalyzed C3-cyanation of indoles via direct C–H functionalization was achieved utilizing CH₃CN as the cyanide source through transition-metal-catalyzed C–CN bond cleavage.