Electrochemical Synthesis of 2-Amino-1,3-benzoxazines via TBAI-mediated Desulfurative Cyclization of Isothiocyanates and 2-Aminobenzyl Alcohols

An efficient one-step protocol has been developed to access a variety of 2-amino-1,3-benzoxazine derivatives via tetrabutylammonium iodide-mediated electrochemical desulfurative cyclization of isothiocyanates and 2-aminobenzyl alcohols. The reaction proceeds through a cycle involving in situ iodine generation, desulfurative cyclization, and iodide regeneration, efficiently forming intermolecular C-O and C-N bonds and affording 2-amino-1,3-benzoxazines in moderate to excellent yields. The practical utility of this strategy is evidenced by its broad substrate scope, good functional group compatibility, scalability to gram-scale synthesis, and metal- and oxidant-free conditions.

Development and assessment of novel pyrazole-thiadiazol hybrid derivatives as VEGFR-2 inhibitors: design, synthesis, anticancer activity evaluation, molecular docking, and molecular dynamics simulation

Cancer remains a significant health challenge globally, requiring the development of targeted chemotherapeutics capable of specifically inhibiting cancer cell growth. Angiogenesis is one of the key features of tumor growth and metastasis and is, therefore, an important target for the treatment of many tumors. The vascular endothelial growth factor (VEGF) signaling pathway has proven to be a promising lead in anticancer therapy due to the central role it plays in tumor angiogenesis. Vascular endothelial growth factor receptor-2 (VEGFR-2) is a key mediator in the signaling pathway regulating angiogenesis. Targeting VEGFR-2 may disrupt angiogenesis, leading to a reduction in tumor blood supply and tumor progression. The design, synthesis, and assessment of novel VEGFR-2 inhibitor derivatives are the focus of this study, with particular emphasis on incorporating the pyrazole-thiadiazol pharmacophore into the molecular structure. Taking advantage of the pharmacophoric properties of pyrazole and 1,3,4-thiadiazol, compounds with different substituents in the main structure were designed and synthesized. The compounds were also evaluated for antiproliferative activity against cancer cell lines. Compound 4e demonstrated the highest activity among all compounds, with an IC50 of 9.673 ± 0.399 μM against HT-29 cells and 23.081 ± 0.400 μM against NIH3T3 cells. To further support the inhibitory activity of compound 4e, an in silico study was performed. Compound 4e demonstrated strong binding to the active site of VEGFR-2 in molecular docking studies, forming hydrogen bonds with key amino acid residues. The stability of the compound in the enzyme's active site was demonstrated through molecular dynamics simulations.

Electrochemical Sulfonylation/Cyclization of N-Alkenylacrylamides with Sodium Sulfinates or Sulfonyl Hydrazides

Two general protocols for the regioselective electrochemically enabled sulfonylation cyclization of N-alkenylacrylamides with sodium sulfinates or sulfonyl hydrazides were described. These methods were carried out under mild, chemical oxidant-free, and transition-metal-free conditions with a broad substrate scope and good functional group tolerance to provide sulfonyl-containing 4-pyrrolin-2-ones, which is readily scalable to the gram scale.

Synthesis of isothiocyanato alkyl sulfides from alkenes using KSCN and DMTSM

A method for the synthesis of isothiocyanato alkyl sulfides from KSCN and DMTSM under metal-free conditions has been developed. The features of this reaction are low-cost, readily accessible starting materials and the use of KSCN as nucleophiles for C-NCS bond formation. Alkenes with various substituted groups react smoothly and the desired products are obtained in moderate to good yields.

Isothiocyanates: happy-go-lucky reagents in organic synthesis

Owing to their unique structural features, isothiocyanates (ITCs) are a class of highly useful and inimitable reagents as the -NCS group serves both as electrophile and nucleophile in organic synthesis. ITCs share a rich legacy in organic, medicinal, and combinatorial chemistry. Compared to their oxygen equivalents, isocyanates, ITCs are easily available, less unpleasant, and somewhat less harmful to work with (mild conditions) which makes them happy-go-lucky reagents. Functionalized ITCs can finely tune the reactivity of the -NCS group and thus can be exploited in the late-stage functionalization processes. This review's primary aim is to outline ITC chemistry in the construction and derivatization of heterocycles through the lens of sustainability. For ease and brevity, the sections are divided based on reactive centers present in functionalized ITCs and modes of cyclisation. Scrutinizing their probable unexplored directions for future research studies is also addressed.

Electrochemical or Photoelectrochemical Alkenylpolyfluoroalkylation of 3-Aza-1,5-dienes: Regioselective Entry to Polyfluoroalkylated 4-Pyrrolin-2-ones

An electrochemical or photoelectrochemical regioselective polyfluoroalkylation/cyclization cascade of 3-aza-1,5-dienes with sodium fluoroalkanesulfinates is presented. This protocol proceeds with a broad substrate scope and good functional group tolerance under mild, oxidant-free, transition-metal-free, and electrolyte-free conditions to provide 3-polyfluoroalkylated 4-pyrrolin-2-ones in one step from readily available N-vinylacrylamides, and it is readily scalable to the Gram scale.

Chemodivergent Photocatalyzed Heterocyclization of Hydrazones and Isothiocyanates for the Selectivity Synthesis of 2-Amino-1,3,4-thiadiazoles and 1,2,4-Triazole-3-thiones

A photocatalytic chemodivergent reaction for the selectivity formation of C-S and C-N bonds in a controlled manner was proposed. The reaction medium, either neutral or acidic, is critical to dictate the formation of 2-amino-1,3,4-thiadiazoles and 1,2,4-triazole-3-thiones from isothiocyanates and hydrazones. This is a practical protocol to achieve the chemoselectivity under mild and metal-free conditions.

Electro-organic synthesis: an environmentally benign alternative for heterocycle synthesis

Heterocyclic compounds are considered to be one of the most established structural classes due to their extensive application in agrochemicals, pharmaceuticals and organic materials. Over the past few years, the development of heterocyclic compounds has gone through a considerable renaissance from conventional traditional methodologies to non-conventional electro-organic synthesis. Replacing metal catalysts, strong oxidants and multi-step methodologies with metal and strong oxidant-free single-step protocols has revolutionized the field of sustainable organic synthesis. Electro-organic synthesis has evolved as a scalable and sustainable approach in different synthetic protocols in an environment-benign manner. The current review outlines the recent developments in C-C, C-N, C-S and C-O/Se bond formation for heterocycle synthesis using electrochemical methods. Different synthetic strategies and their detailed mechanistic description are presented to enlighten the future applications of electrochemistry in heterocycle synthesis.

Electroreductive synthesis of polyfunctionalized pyridin-2-ones from acetoacetanilides and carbon disulfide with oxygen evolution

A chemical reductant or a sacrificial electron donor is required in any reduction reactions, generally resulting in undesired chemical waste. Herein, we report a reductant-free reductive [3 + 2 + 1] annulation of β-keto amides with CS₂ enabled by the synergy of electro/copper/base using water as an innocuous anodic sacrifice with O₂ as a sustainable by-product. This electrochemical protocol is mild and provides access to polyfunctionalized pyridin-2-ones from simple starting materials in a single step.

Electrooxidation-induced selective cleavage of C–N bonds of tertiary amines to access thioureas, selenoureas, and 2-aminated benzoselenazoles

A metal-free, operationally simple, and scalable electrooxidation-induced selective cleavage of C–N bonds of tertiary amines to access thiourea, selenourea, and 2-aminated benzoselenazole derivatives has been developed.

Exploring the regioselectivity of the cyanoalkylation of 3-aza-1,5-dienes: photoinduced synthesis of 3-cyanoalkyl-4-pyrrolin-2-ones

Regioselective cyanoalkylalkenylation of 3-aza-1,5-dienes with oxime esters induced by visible light.

Base-promoted Cyclization Reaction of o-Isothiocyanato Arylacetylenes and Aroylacetonitriles: Easy Access to Benzo[d][1,3]thiazines

A green and efficient synthesis of benzo[d][1,3]thiazines through base-promoted cyclization reaction of o-isothiocyanato arylacetylenes with aroylacetonitriles has been developed. This protocol displays high step economy and efficiency, and tolerates various...

Design, Synthesis, Biological Evaluation, and Computational Studies of Novel Fluorinated Candidates as PI3K Inhibitors: Targeting Fluorophilic Binding Sites

Highly fluorinated candidates containing anticancer pharmacophores like thiosemicarbazone (5a-e) and its cyclic analogues hydrazineylidenethiazolidine (6a-e), 2-aminothiadiazole (7a-e), and 2-hydrazineylidenethiazolidin-4-one (8a-e) were synthesized, and their cytotoxic activity was assayed against 60 tumor cell lines. Compounds 6c, 7b, and 8b displayed the most potent activity with lower toxic effects on MCF-10a. In vitro phosphatidylinositol 3-kinase (PI3K) enzyme inhibition was performed. Compound 6c displayed half-maximal inhibitory concentration (IC₅₀, μM) values of 5.8, 2.3, and 7.9; compound 7b displayed IC₅₀ values of 19.4, 30.7, and 73.7; and compound 8b displayed IC₅₀ values of 77.5, 53.5, and 121.3 for PI3Kα, β, and δ, respectively. Moreover, cell cycle progression caused cell cycle arrest at the S phase for compounds 6c and 8b and at G1/S for compound 7b, while apoptosis was induced. In silico studies; molecular docking; physicochemical parameters; and absorption, distribution, metabolism, excretion, and toxicity (ADMET) analysis were performed. The results showed that compound 6c is the most potent one with a selectivity index (SI) of 39 and is considered as a latent lead for further optimization of anticancer agents.