Bench‐Stable Electrophilic Indole and Pyrrole Reagents: Serendipitous Discovery and Use in C–H Functionalization

Caramenti, Paola; Waser, Jérôme

doi:10.1002/hlca.201700221

Cited by 20 publications

(10 citation statements)

References 139 publications

(190 reference statements)

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“…reported indole and pyrrole C−H heteroarylation by using indoleBX reagents in the presence of rhodium catalyst (Scheme 72). The mild conditions allowed the tolerance of a broad functional groups, including halogens, ethers and boronic esters [78] …”

Section: Transformations Involving Hypervalent Iodine Reagents and 2 ...mentioning

confidence: 99%

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

et al. 2022

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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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Section: Transformations Involving Hypervalent Iodine Reagents and 2 ...mentioning

confidence: 99%

“…The mild conditions allowed the tolerance of a broad functional groups, including halogens, ethers and boronic esters. [78]…”

Section: Cà H Heteroarylationmentioning

confidence: 99%

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

et al. 2022

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“…The desired heteroarylated products were obtained in good yields as single regiosiomers using either pyridines (66ac) or methoxamides (67a-c) directing groups. [64][65] Heteroarylated 2-an 4-pyridones 68 and 69 and quinoline N-oxide 70 could also be accessed (Scheme 35c). 67 Finally, the method could be extended to ortho-hydroxy and amido benzaldehydes using either a Rh(III) or an Ir(III) catalyst (Scheme 35d, products 71-73).…”

Section: Metal-catalyzed C-h Functionalization With Indolebxs and Pyrmentioning

confidence: 99%

“…64−66 C3substituted-indole and pyrrole BX reagents 62−64 were accessed from the heterocycles by the Lewis acid catalyzed addition to acetoxybenziodoxol(on)es (Scheme 34a). 64,65 C2substituted indole BX reagents 65a−c were obtained by reaction of trifluoroborate salts with fluorobenziodoxole (Scheme 34b). 66…”

Section: Decarboxylative Cyanation Of Carboxylic Acidsmentioning

confidence: 99%

“…In 2017, we reported the serendipitous discovery of a novel class of stable cyclic indole- and pyrrole-based BX reagents. − C3-substituted-indole and pyrrole BX reagents 62 – 64 were accessed from the heterocycles by the Lewis acid catalyzed addition to acetoxybenziodoxol(on)es (Scheme a). , C2-substituted indole BX reagents 65a – c were obtained by reaction of trifluoroborate salts with fluorobenziodoxole (Scheme b) …”

Section: Electrophilic Indoles and Pyrrolesmentioning

confidence: 99%

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Cyclic Hypervalent Iodine Reagents: Enabling Tools for Bond Disconnection via Reactivity Umpolung

2018

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Conspectus The efficient synthesis of organic compounds is an important field of research, which sets the basis for numerous applications in medicine or materials science. Based on the polarity induced by functional groups, logical bond disconnections can be deduced for the elaboration of organic compounds. Nevertheless, this classical approach makes synthesis rigid, as not all bond disconnections are possible. The concept of Umpolung has been therefore introduced: by inverting the normal polarity of functional groups, new disconnections become possible. Among the tools for achieving Umpolung, hypervalent iodine reagents occupy a privileged position. The electrophilicity of the iodine atom and the reactivity of the hypervalent bond allow access to electrophilic synthons starting from nucleophiles. Nevertheless, some classes of hypervalent iodine reagents can be too unstable for many applications, in particular involving metal catalysis. In this context, cyclic hypervalent iodine reagents, especially benziodoxolones (BXs), have been known for a long time to be more stable than their acyclic counterparts, yet their synthetic potential had not been fully exploited. In this Account, we report our efforts since 2008 on the use of BX reagents in the development of new transformations in organic synthesis, which showed for the first time their versatility as synthetic tools. Our work started with electrophilic alkynylation, as alkynes are one of the most important functional groups in organic chemistry, but are usually introduced as nucleophiles. We used ethynylbenziodoxolones (EBXs) in the direct alkynylation of nucleophiles, such as keto esters, thiols, or phosphines. The reagents could then be applied to the gold- and palladium-catalyzed alkynylation of C–H bonds on (hetero)arenes, leading to a more efficient alternative to the Sonogashira reaction. More complex reactions were then developed with formations of several bonds in a single transformation. Gold- and platinum-catalyzed cyclization/alkynylation domino processes gave access to new types of alkynylated heterocycles. Multifunctionalization of olefins became possible through intramolecular oxy- and amino-alkynylations. (Enantioselective) copper-catalyzed oxy-alkynylation of diazo compounds led to stereocenters with perfect atom economy. Finally, EBXs were also used for the alkynylation of radicals generated under photoredox conditions. Since 2013, we then extended the use of BX reagents to other transformations. Azidobenziodoxol(on)ess (ABXs) were used in the azidation of keto esters, enol silanes, and styrenes. New more stable derivatives were introduced. Cyanobenziodoxolones (CBXs) enabled the cyanation of stabilized enolates, thiols, and radicals. Finally, new BX reagents were developed for the Umpolung of indoles and pyrroles. They could be used in metal-catalyzed directed C–H functionalizations, as well as in Lewis acid mediated oxidative coupling to give functionalized bi(hetero)arenes. In the past decade, our group and others have shown that BX reag...

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Recent Progress in Synthetic Applications of Cyclic Hypervalent Iodine(III) Reagents

2023

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Hypervalent iodine compounds have found broad application in modern organic chemistry as reagents and catalysts. Cyclic hypervalent iodine reagents based on the benziodoxole heterocyclic system have higher stability compared to their acyclic analogues, which makes possible the preparation and safe handling of the reagents with special ligands such as azido, cyano, and trifluoromethyl groups. Numerous iodine‐substituted benziodoxole derivatives have been prepared and utilized as reagents for transfer of the substituent on hypervalent iodine to organic substrate. Reactions of these reagents with organic substrates can be performed under metal‐free conditions, in the presence of transition metal catalysts, or using photocatalysts under photoirradiation conditions. In this review, we focus on the most recent synthetic applications of cyclic hypervalent iodine(III) reagents with the following ligands: N3, NHR, CN, CF3, SCF3, OR, OAc, ONO2, and C(=N2)CO2R. The review covers literature published mainly in the last 5 years.magnified image

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Bench‐Stable Electrophilic Indole and Pyrrole Reagents: Serendipitous Discovery and Use in C–H Functionalization

Cited by 20 publications

References 139 publications

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

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

Cyclic Hypervalent Iodine Reagents: Enabling Tools for Bond Disconnection via Reactivity Umpolung

Recent Progress in Synthetic Applications of Cyclic Hypervalent Iodine(III) Reagents

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