Hypervalent Iodine‐Catalyzed Oxidative Functionalizations Including Stereoselective Reactions

Singh, Fateh V.; Wirth, Thomas

doi:10.1002/asia.201301582

Cited by 318 publications

(115 citation statements)

References 178 publications

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“…[16] Nevertheless,t here are only af ew examples of iodine(III)-catalyzed fluorinativet ransformationsb yK itamura, [17] Shibata, [7] and Jacobsen's group, [18] except for the electrochemical fluorination reactions by Fuchigami and Hara's groups. [16] Nevertheless,t here are only af ew examples of iodine(III)-catalyzed fluorinativet ransformationsb yK itamura, [17] Shibata, [7] and Jacobsen's group, [18] except for the electrochemical fluorination reactions by Fuchigami and Hara's groups.…”

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confidence: 99%

Catalytic Cycloisomerization–Fluorination Sequence of N‐Propargyl Amides by Iodoarene/HF⋅Pyridine/Selectfluor Systems

et al. 2016

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As af irst example of metal-free and catalytic fluorinative transformationsofalkynes, we developed acycloisomerization-fluorination sequence of N-propargyl amides catalyzed by an iodine(III) species. The iodine(III) catalyst is in situ generated from iodoarene as aprecatalyst with Selectfluor as af luorinating oxidant in the presence of HF·pyridine.Fluorines ubstituents show am arked improvemento fp roperties, such as solubility,b ioavailability, and metabolic stability, in many examples of introducing fluorine into pharmaceuticals and bioactive substances. [1] Accordingly,e fficient introduction methods of fluorine into organic compounds have received much attention recently. [2] Amongt hem,t he combination of cyclization and fluorination reaction in as ingle operation provides highly efficient approaches to give fluorinated heterocycles from unsaturated compounds bearing ah eteroatom nucleophile. For the synthesis of fluorinated aliphatic heterocycles, variousm etal-catalyzed intramolecular aminofluorination [3] and oxyfluorinationr eactions [4] of alkenes [5] or their metal-free methods [6,7] have been developed. In contrastt ot he reactions of alkenes, the cycloisomerization-fluorination sequence of alkynes has been less studied. [8,9] Althoughg old catalysts with Selectfluor have been well employed for this sequence, the catalytic systemsw ere not effective on that of N-propargyl amides (see the Supporting Information). Also, to the best of our knowledge, metal-free methods for such sequence have not been achievedy et. Moreover,b ecause halocyclization reactions of N-propargyl amides by general halogenating reagents hardly bring about aromatization to halogenated oxazoles, [10] one-pot two-step methods, including metal catalysis for the synthesis of halogenated oxazoles, have been developed by Hashmi's and other groups(Scheme 1a). [10b,c, 11] One the other hand, as part of our studies on the metal-free synthesis of aromatic heterocyclest hrough the activation of alkynes by hypervalent iodine(III) reagents, [12] we have recently found the cycloisomerization-acetoxylation sequence of Npropargyl amides with PhI(OAc) 2 (PIDA) (Scheme 1b). [12a] This reaction, which can afford oxazoles bearing the acetoxyg roup in as ingleo peration, inspired us to examine the formation of fluorinated oxazoles. Herein, ametal-free and catalytic cycloisomerization-fluorinations equence of N-propargyl amides mediated by iodine(III) is described (Scheme 1c).In recent years, there has been ac onsiderable growth in the application of hypervalent iodine reagents to organic syntheses due to their low toxicity and transition-metal-like reactivities, such as an activation of unsaturated bonds, reductive elimination, and ligand exchange. [13] Particularly,( difluoroiodo)arenes (ArIF 2 )c an be used in fluorinative transformations of unsaturated compounds withouta ny metal catalysts. [14] These procedures have been extended to some metal-free cycloisomerization-fluorinationr eactions of alkenes. [15] For example, Hara et al. repo...

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Catalytic Cycloisomerization–Fluorination Sequence of N‐Propargyl Amides by Iodoarene/HF⋅Pyridine/Selectfluor Systems

et al. 2016

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“…Although the first λ 3 ‐aryl iodine, the dichloro iodobenzene 1 (see Scheme ), was prepared by the German chemist Conrad Willgerodt in 1886, it took almost 100 years until hypervalent iodine(III) compounds developed from a laboratory curiosity to a powerful and versatile tool in organic synthesis . Besides their application in ‘simple’ oxidations of alcohols, λ 3 ‐iodanes have found their way into a multitude of different reactions, such as cyclizations,,,, atom‐transfer reactions,,,, oxidative rearrangements, and fragmentations, α‐functionalizations of carbonyl compounds,,, and even asymmetric synthesis –,. Within the last 20 years, the development of hypervalent iodine(III) chemistry has tremendously accelerated.…”

Section: Introductionmentioning

confidence: 99%

Advances in Iodine(III)‐Mediated Halogenations: A Versatile Tool to Explore New Reactivities and Selectivities

Arnold

Ulmer

Gulder

2016

Chemistry A European J

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Within the repertoire of organic chemical transformations, the halogenation of substrates is among the most versatile, reliable, and broadly applicable reactions. Although a multitude of different methods are known today, there is still a huge demand for novel and, in particular, catalytic halogenation methods that exhibit new reactivities and selectivities. The class of hypervalent iodanes meets exactly these needs and thus offers a great opportunity to fuel this highly desirable direction within the field of halogenation chemistry. This Concept gives a short overview of recent examples focusing on selective and/or mechanistically unusual halogenations.

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“…The chemistry and synthetic applicationso fp olyvalent iodine have been discussed in many reviews. [1,5,9,10] Recently,t hese reagents have been successfully employed to extend the scope of selective oxidative transformationso fc omplex organic molecules. [7] In this Focus Review,r ecent developments in oxidative cyclization reactions, in particulart hose of hydrazones, [11] that use hypervalent iodine(III) reagents-specifically iodobenzenediacetate-in the synthesis of triazoles, in particular fused triazoles, are described.…”

Section: Introductionmentioning

confidence: 99%

Hypervalent‐Iodine(III)‐Mediated Oxidative Methodology for the Synthesis of Fused Triazoles

Kamal

Kumar

2016

Chemistry An Asian Journal

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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.

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Hypervalent Iodine‐Catalyzed Oxidative Functionalizations Including Stereoselective Reactions

Cited by 318 publications

References 178 publications

Catalytic Cycloisomerization–Fluorination Sequence of N‐Propargyl Amides by Iodoarene/HF⋅Pyridine/Selectfluor Systems

Catalytic Cycloisomerization–Fluorination Sequence of N‐Propargyl Amides by Iodoarene/HF⋅Pyridine/Selectfluor Systems

Advances in Iodine(III)‐Mediated Halogenations: A Versatile Tool to Explore New Reactivities and Selectivities

Hypervalent‐Iodine(III)‐Mediated Oxidative Methodology for the Synthesis of Fused Triazoles

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