Several reactions mended by hypervalent iodine reagents have been developed in aqueous media recently. The evolution of reactions using hypervalent iodine reagents in aqueous medium is one of the most vital fields in organic synthesis to achieve one of the requirements of green chemistry. Hypervalent iodine reagents have the potential to replace toxic metals in numerous chemical reactions viz. oxidation reactions, coupling reactions, α-functionaliztion reactions, cyclization reactions and halogenations reactions etc. due to their stability, high selectivity, easy and simple experimentation, less toxic nature. In a chemical reaction solvents are required for several functions viz. in extractions, reactants solubility, washing and separation of final products. Water as a medium represents a safe, non-toxic, inexpensive and environmentally friendly alternative to toxic organic solvents for various organic reactions. The evolution of hypervalent iodine reagents with modified reactivities in aqueous phase now enable such chemical reactions which were thought to be illogical only a century ago. Therefore, in the present review, we summarize the various aqueous mediated reactions involving hypervalent iodine reagents.

This review outlines the progress over recent years in the reactions involving combined approach of hypervalent iodine reagents and transition metals such as palladium, nickel, iridium, gold, rhodium, copper, iron, ruthenium, platinum, silver, zinc, rhenium and cobalt. This approach enables organic transformations complimentary to traditional manifolds. Hypervalent iodine reagents play a preeminent role in organic chemistry due to their versatile reactivity, heteroatom ligands and mild reaction conditions. These reagents in combination of transition metal compounds are used in many synthetically useful organic reactions such as oxidation, rearrangement, amination, halogenation, amidation, ring-opening, cyclization and CÀ H and CÀ C functionalization reactions, etc. which are discussed here. Combination with Cobalt 2.3. Reactions of Hypervalent Iodine Reagents with Copper 2.4. Reactions of Hypervalent Iodine Reagents in Combination with Nickel 2.5. Reactions of Hypervalent Iodine Reagents in Combination with Zinc 3. Transformations Involving Hypervalent Iodine Reagents and 2 nd Transition Series Metals 3.1. Reactions of Hypervalent Iodine Reagents in Combination with Ruthenium 3.2. Reactions of Hypervalent Iodine Reagents in Combination With Rhodium 3.3. Reactions of Hypervalent Iodine Reagent in Combination With Palladium 3.4. Reactions of Hypervalent Iodine Reagents in Combination with Silver 4. Transformations Involving Hypervalent Iodine Reagents and 3rd Transition Series Metals 4.1. Reactions of Hypervalent Iodine Reagents in Combination with Rhenium 4.2. Reactions of Hypervalent Iodine Reagents in Combination with Iridium 4.3. Reactions of Hypervalent Iodine Reagents in Combination with Platinum 4.4. Reactions of Hypervalent Iodine Reagents in Combination with Gold 5. Conclusion

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An iodobenzene diacetate (IBD)-mediated simple and green method was determined for the intramolecular oxidative cyclization of 3-aryl-2-pyridiylhydrazones of different aromatic aldehydes in an aqueous medium at room temperature. This efficient strategy provides a route to the synthesis of 3-aryl-1,2,4-triazolo[4,3-a]pyridines in water which eliminates the requirement to use costly and unsafe volatile organic solvents. All reactions were carried out by just stirring the reaction components in water at room temperature. This protocol provides a wide substrate scope and good functional group tolerance.