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This review summarizes structural and synthetic aspects of heterocyclic molecules incorporating an atom of a hypervalent main-group element. The higher thermal stability of hypervalent heterocycles, as compared to their acyclic analogs, adds special feature to their chemistry. 

Abstract A series of new isoxazole‐substituted aryl iodides1 a–1 dhave been synthesized by DIB‐mediated [3+2] cycloaddition reaction of 2‐iodo‐1,3‐bis(prop‐2‐yn‐1‐yloxy) benzene (4) with corresponding benzaldehyde oximes5 a–5 d. Structure of the synthesized aryl iodides1were characterized by IR,¹H NMR,¹³C NMR and HRMS. The structure of1 awas also confirmed by single‐crystal X‐ray crystallography. Further, catalytic activity of iodoarenes1 a–1 dwas screened for the oxidation of hydroquinones and sulfides. On oxidation using aryl iodides1withm‐CPBA as terminal oxidant, hydroquinones afforded benzoquinones while sulfides gave corresponding sulfoxides in good to excellent yields. Iodoarene1 bshowed the best catalytic activity for the oxidation of sulfides and hydroquinones. Moreover, iodoarene1 b, was also utilized for α‐oxytosylation of acetophenones. 

This study provides a greener peptide coupling method using triarylphosphine and recyclable bicyclic benziodazolone, which acts as an oxidant for phosphine as well as base. 

Hypervalent iodine reagents are in high current demand due to their exceptional reactivity in oxidative transformations, as well as in diverse umpolung functionalization reactions. Cyclic hypervalent iodine compounds, known under the general name of benziodoxoles, possess improved thermal stability and synthetic versatility in comparison with their acyclic analogs. Aryl-, alkenyl-, and alkynylbenziodoxoles have recently received wide synthetic applications as efficient reagents for direct arylation, alkenylation, and alkynylation under mild reaction conditions, including transition metal-free conditions as well as photoredox and transition metal catalysis. Using these reagents, a plethora of valuable, hard-to-reach, and structurally diverse complex products can be synthesized by convenient procedures. The review covers the main aspects of the chemistry of benziodoxole-based aryl-, alkynyl-, and alkenyl- transfer reagents, including preparation and synthetic applications. 

Abstract Hypervalent iodine (HVI) reagents have gained much attention as versatile oxidants because of their low toxicity, mild reactivity, easy handling, and availability. Despite their unique reactivity and other advantageous properties, stoichiometric HVI reagents are associated with the disadvantage of generating non-recyclable iodoarenes as waste/co-products. To overcome these drawbacks, the syntheses and utilization of various recyclable hypervalent iodine reagents have been established in recent years. This review summarizes the development of various recyclable non-polymeric, polymer-supported, ionic-liquid-supported, and metal–organic framework (MOF)-hybridized HVI reagents. 1 Introduction 2 Polymer-Supported Hypervalent Iodine Reagents 2.1 Polymer-Supported Hypervalent Iodine(III) Reagents 2.2 Polymer-Supported Hypervalent Iodine(V) Reagents 3 Non-Polymeric Recyclable Hypervalent Iodine Reagents 3.1 Non-Polymeric Recyclable Hypervalent Iodine(III) Reagents 3.2 Recyclable Non-Polymeric Hypervalent Iodine(V) Reagents 3.3 Fluorous Hypervalent Iodine Reagents 4 Ionic-Liquid/Ion-Supported Hypervalent Iodine Reagents 5 Metal–Organic Framework (MOF)-Hybridized Hypervalent Iodine Reagents 6 Conclusion