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The organic chemistry of hypervalent organoiodine compounds has been an area of unprecedented development. This surge in interest in the use of hypervalent iodine compounds has mainly been owing to their highly selective oxidizing properties, environmentally benign character and commercial availability. Hypervalent iodine reagents have also been used as an alternative to toxic heavy metals, owing to their low toxicity and ease of handling. Hypervalent organoiodine(III) reagents are versatile oxidants that have been successfully employed to extend the scope of selective oxidative transformations of complex organic molecules in synthetic chemistry. This Focus Review concerns the tandem in situ generation and 1,5-electrocyclization of N-heteroaryl nitrilimines into fused triazoles. We describe the importance of recently developed hypervalent-organoiodine(III)-catalyzed oxidative cyclization reactions, building towards the conclusion that hypervalent iodine chemistry is a promising frontier for oxidative cyclization, in particular of hydrazones, for the synthesis of fused triazoles.

A series of geminal β,β-ditosyloxy ketones were synthesized in moderate to good yields through hydroxy(tosyloxy)iodobenzene-mediated ditosyloxylation of readily accessible α,β-unsaturated ketones in a polar aprotic solvent. A mechanism has been proposed for the synthesis of the geminal β,β-ditosyloxy ketones, and entails an oxidative rearrangement involving a 1,2-aryl migration.

This review article epitomize the different synthetic approaches to synthesize α,β‐chalcone dibromide and their application in developing chemically and biologically relevant heterocyclic compounds. The transformation of α,β‐chalcone dibromide into aziridines, pyrazolines, pyrazoles, isoxazoles, pyridine, pyrimidine, flavanoids, diazepines and other heterocyclic compounds has been described briefly in different categories to highlight the importance of these α,β‐chalcone dibromide as key intermediate in organic chemistry. Stereoselective debromination of α,β‐chalcone dibromides with various metal‐containing reducing agents, metal‐metal salt system, ionic liquid, solvents and photoredox catalyst to their corresponding chalcones is also described.

An efficient synthesis of novel 3-(3-aryl-1-phenyl-1H-pyrazol-4-yl)-5,7-dimethyl-[1,2,4]triazolo[4,3-a]-pyrimidines was accomplished by the oxidation of pyrimidinylhydrazones by using organoiodine(III) reagent. All new triazolopyrimidine derivatives bearing the pyrazole scaffold were screened to evaluate them as a reproductive toxicant in the testicular germ cells of goat (Capra hircus). This study aimed at assessing the cytological and biochemical changes in testicular germ cells after the exposure to triazolopyrimidines in a dose- and time-dependent manner. Histomorphological analysis, fluorescence assays, apoptosis quantification, and terminal deoxynucleotidyl transferase dUTP-mediated nick-end labeling (TUNEL) assays were performed to determine cytological changes, whereas thiobarbituric acid-reactive substance (TBARS) and ferric reducing antioxidant power (FRAP) assays were carried out to measure the oxidative stress in triazolopyrimidines treated germ cells. The parallel use of these methods enabled us to determine the role of triazolopyrimidines in inducing apoptosis as a consequence of cytogenetic damage and oxidative stress generated in testicular germ cells of goat.

The given study investigates and validates [hydroxy (tosyloxy)iodo]benzene (HTIB) mediated oxidative 1,2-aryl CÀ C migration in variegated α,β-unsaturated diaryl ketones. This oxidative-skeletal rearrangement ultimately outgrowth to α-aryl-β,β-ditosyloxy ketones in presence of CH 2 Cl 2 . The structure of products has been very well established using various spectral techniques 1 H & 13 C-NMR, IR and single crystal XRD. The generality of fascinating 1,2-aryl CÀ C migration was thoroughly investigated and verified by electronic (EDG/EWG) and steric factors on different derivatives of α,β-unsaturated diaryl ketones. Mechanism of 1,2-aryl CÀ C migration has also been supported by computational studies using B3LYP-D3 level of theory. Aesthetically this novel and unique three carbon component would expose a direct and conceptually robust strategy to access regioselective synthesis of 4,5-diaryl isoxazoles, 4,5-diaryl pyrazoles and 1,4,5-triaryl pyrazoles and also efficient access to desoxybenzoin and other important β,β-difunctionalized chemical entities.

Azole nucleus represents an important class of biologically active compounds that are gaining more attention in the field of medicinal chemistry due to large number of structure diversity. Among azoles, pyrazoles, and isoxazoles fivemembered nitrogen containing heterocyclic compounds are associated wide range of biological activities such as anticancer, antimicrobial, anti-inflammatory, antioxidant, etc. Some of azole derivatives (e.g., 1,4,5-trisubstituted pyrazoles, 4,5-disubstituted isoxazoles, and 4,5-disubstituted-1H-pyrazoles) are still unexplored in literature, these unexplored azoles have fascinated the consideration of many researchers to study their framework synthetically and biologically. This present review is an attempt to update and understand the chemistry of unexplored pyrazoles and isoxazoles along with their medicinal importance. This article would definitely help the researchers to bring further enhancement in the synthesis of biologically active pyrazoles and isoxazoles.

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