Combined Approach of Hypervalent Iodine Reagents and Transition Metals in Organic Reactions

Abstract

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

Recent progress in alkynylation with hypervalent iodine reagents

“…Over the last two decades, the combination of hypervalent iodine reagents with gold, 91 and other transition-metals has allowed the functionalization of a broad range of substrates. 21 For example, the Hashmi group reported a bimetallic gold–silver catalytic system for the synthesis of 3-alkynyl benzofurans from phenols and EBx reagents ( Scheme 21 ). 92 Mechanistic studies, suggested that a bimetallic Au–Ag catalyst promoted a tandem ortho C(sp 2 )–H alkynylation/oxyalkynylation reaction by leveraging the exceptional redox property and carbophilic π-acidity of gold.…”

“…10 Since the discovery of the exceptional reactivity of the hypervalent bond, hypervalent iodine reagents have attracted the interest of synthetic chemists. [13][14][15][16][17][18][19][20][21] In particular, alkynyl iodonium salts and ethynylbenziodoxolone (EBX) reagents have been particularly prolific as electrophilic alkyne synthons. [22][23][24][25] The peculiar reactivity of hypervalent iodine reagents arises from the 3-center-4-electron bond or hypervalent bond, which is longer, more polarized and weaker than a standard covalent bond leading to a higher electrophilic reactivity (Scheme 2A).…”

“…10 Since the discovery of the exceptional reactivity of the hypervalent bond, hypervalent iodine reagents have attracted the interest of synthetic chemists. 13–21 In particular, alkynyl iodonium salts and ethynylbenziodoxolone (EBX) reagents have been particularly prolific as electrophilic alkyne synthons. 22–25…”

Applications of phenyliodine(III) diacetate in heterocyclic ringformations: An updatefrom 2015 to date

“…The need for iodine organic compounds has risen since then. Hypervalent iodine reagents are widely utilized as oxidants and electrophilic reagents in organic synthesis [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Hypervalent iodine reagents exhibit radical-type reactions, homolytic reactions, and singleelectron transfer (SET) reactions under the appropriate conditions.…”

Oxidative Nickel-Catalyzed ortho-C–H Amination of (Iso)quinolines with Alicyclic Amines Directed by a Sacrificial N-Oxide Group

“…Therefore, construction of the C­(pyridyl)–N­(alicyclic) bond is of fundamental importance in synthetic and medicinal chemistry . In the C–N bond forming toolbox, direct heteroaryl C–H/N–H coupling should be an ideal adoption as it eliminates extra costly steps to prefunctionalize either coupling partner. , However, unlike the exceptionally broad arene (especially those with Py ring-contained DGs) ,− and five-membered heterocyclic substrates (Scheme a and b), C–H bond aminations of a free or fused Py ring with free amines (especially aliphatic amines) still remain underdeveloped because primary/secondary amines and Py rings have the tendency to adopt a nonproductive N-bound coordination mode with TMs, to result in a significant decrease of catalytic reactivity (Scheme c) . To this end, it is highly desirable to explore ideal C–H amination on a free or fused Py ring, wherein developing more reactive TM catalysis or installing easily removable DGs with weaker coordination capability on pyridyl-nitrogen atoms is a potential solution.…”