Arylation of Tetrazolide With Diaryliodonium Halides: Evidence for Intermediacy of Benzyne

Akiyama, Tetsuo; Imasaki, Yoshio; Kawmisi, Mituyosi

doi:10.1246/cl.1974.229

Cited by 41 publications

(22 citation statements)

References 5 publications

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“…(Scheme 3.6, bottom reaction). 78 Later, another work was published that further confirmed this type C-H deprotonation of diaryliodonium salts. In this work, diphenyliodonium chloride was reacted with sodium acetate and a benzyne trap, 1,2,3,4-tetraphenylcyclopentadienone, was added in the reaction mixture.…”

Section: Literature Precedent For the Generation Of Arynes Via C-h Dementioning

confidence: 88%

“…78 In the seminal reports of reactions of diaryliodonium salts by Beringer and Forgione, which proposed the mechanisms of radical-pair and nucleophilic substitution, aryne pathway was also suggested but without sufficient compelling evidence. 79 Hence the authors from Kyoto University pursued a mechanistic investigation to demonstrate a plausible pathway taking place with diaryliodonium salts.…”

Section: Literature Precedent For the Generation Of Arynes Via C-h Dementioning

confidence: 99%

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The Discovery and Development of Metal-Free Arylation Reactions with Unsymmetrical Diaryliodonium Salts

Sundalam¹

2000

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Functionalizing arenes and heteroarenes has been an active area of research since the 19th century, due to the presence of these molecular structures in many industrially important sectors. A tremendous amount of research has been published in achieving these chemical transformations using stoichiometric reagents and transition metal -catalyzed reactions. However, challenges still remain. An alternative and comparable methodology to metalcatalyzed reactions to overcome the drawbacks will advance this particular area of research is desirable.Hypervalent iodine compounds offer a promising approach to metal -free arylation reactions. These mild, air and moisture stable compounds have showed significant success as non-toxic and metal-free reagents for the arylation reactions. In particular, unsymmetrical diaryliodonium salts offer functionalization of complex arene structure in a n efficient and sustainable pathway.A base-mediated coupling reaction for the metal -free synthesis of alkylaryl ethers by using unsymmetrical diaryliodonium salts and aliphatic alcohols is described. This method shows broad substrate scope with respec t to both of the coupling partners to produce industrially useful alkyl -aryl ethers in moderate to excellent yields. The reaction is operationally simple, proceeds at mild temperature, and is atom-economical. Sustainability and synthetic utility of this reaction is demonstrated by the use of unsymmetrical aryl(mesityl)iodonium salts as the arylating agents. A limitation of poor reactivity of electron rich unsymmetrical diaryliodonium salts was overcome by designing 2nd generation conditions and using trimethoxy benzene (TMP) as the auxiliary group.Additionally discovery and development of an efficient method to access highly functionalized arynes from unsymmetrical aryl(mesityl)iodonium tosylate salts is presented. The aryne intermediates are generated by ortho C-H deprotonation of aryl(mesityl)iodonium salt with an amide base and subsequently trapped in a cycloaddition reaction with furan in moderate to good yields. Selective iodonium moiety elimination is discussed and the effect of auxiliary and temperature to reduce the regioisomeric ratio is demonstrated. We wish you were still among us

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Section: Literature Precedent For the Generation Of Arynes Via C-h Dementioning

confidence: 88%

Section: Literature Precedent For the Generation Of Arynes Via C-h Dementioning

confidence: 99%

The Discovery and Development of Metal-Free Arylation Reactions with Unsymmetrical Diaryliodonium Salts

Sundalam¹

2000

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“…In addition to the common electrophilic arylation reactions, the arylation reactions of diaryliodonium salts via benzyne species have also been reported. In earlier studies, Akiyama and co‐workers reported that the arylation of sodium tert ‐butoxide 29 with diaryliodonium bromide 30 afforded regioisomeric products 31 and 32 (Scheme ) . The authors suggested that this reaction probably involved benzyne species generated in situ from diaryliodonium salt 30 and sodium tert ‐butoxide 29 .…”

Section: Application Of Diaryliodonium Salts As Benzyne Precursorsmentioning

confidence: 99%

“…The cyclic hypervalent iodine compound, phenylbenziodoxole 1 a (also known as diphenyliodonium‐2‐carboxylate) generates benzyne via decarboxylation at high temperatures . Diaryliodonium salts 1 b can be deprotonated by strong bases at the ortho position followed by elimination of ArI and formation of benzyne . Diaryliodonium salts with a silyl substituent in ortho position such as phenyl[2‐(trimethylsilyl)phenyl]iodonium triflate (Kitamura's reagent) 1 c can produce benzyne species via desilylation by fluoride source .…”

Section: Introductionmentioning

confidence: 99%

Iodonium Salts as Benzyne Precursors

Yoshimura

Saitô

Zhdankin

2018

Chemistry A European J

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Reactions involving benzyne and aryne intermediates have found widespread application in organic synthesis. Various benzyne precursors and benzyne generating procedures are known. Recently, methods of benzyne generation from diaryliodonium salts and related hypervalent iodine compounds have received considerable attention. These methods are characterized by mild reaction conditions and applicability in a broad range of chemical transformations. The present minireview is focused on the preparation and reactivity of hypervalent iodine based benzyne precursors. Furthermore, recent developments in their synthetic application are discussed.

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“…On the other hand, it may underlie a promising procedure for the preparation of difficultly accessible 2-substituted tetrazoles. Known methods for arylation of 5-substituted tetrazoles [1,2] lead to formation of mixtures of isomeric 1,5-and 2,5-disubstituted derivatives. However, in some cases such reactions are characterized by high selectivity.…”

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confidence: 99%

Microwave-assisted arylation of 5-substituted tetrazoles

2010

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SHORT COMMUNICATIONSDespite considerable interest in 2,5-disubstituted tetrazoles as potential substrates for the synthesis of biologically active substances, methods for their preparation have been developed to insufficient extent. Arylation of tetrazole and 5-substituted tetrazoles is one of the least studied reactions of these compounds. On the other hand, it may underlie a promising procedure for the preparation of difficultly accessible 2-substituted tetrazoles. Known methods for arylation of 5-substituted tetrazoles [1, 2] lead to formation of mixtures of isomeric 1,5-and 2,5-disubstituted derivatives. However, in some cases such reactions are characterized by high selectivity. For example, the arylation of 5-substituted tetrazolates [3-6] with diaryliodonium salts in the presence of different catalysts gives only 2,5-disubstituted tetrazoles. The arylation of 5-aryltetrazoles with 2,4-dinitrofluorobenzene also occurs at the 2-position of the tetrazole ring with high selectivity [7].In continuation of our studies on the synthesis of functionally substituted tetrazoles under conditions of microwave activation [8,9], we examined arylation of 5-aryl(alkyl)tetrazoles with 4-nitrofluorobenzene in DMF in the presence of sodium hydroxide under microwave irradiation. We previously showed [2] that the arylation of 5-methylsulfanyltetrazole with 4-nitrofluorobenzene in DMF in the presence of sodium hydroxide yields a mixture of 1,5-and 2,5-disubstituted isomers. However, no arylation of 5-alkyl-or 5-aryltetrazoles occurred under analogous conditions despite microwave activation or conventional heating. Obviously, the reason is low nucleophilicity of tetrazolate ion and competing reaction of 4-nitrofluorobenzene with DMF.We presumed that arylation of 5-alkyl(aryl)tetrazoles could be accomplished in another polar solvent, dimethyl sulfoxide. In fact, the arylation of 5-aryltetrazoles with 4-nitrofluorobenzene in DMSO in the presence of sodium hydroxide under microwave activation or without it (on heating) gave only the corresponding 2,5-diaryltetrazoles. Our results showed that microwave irradiation increases the yield of the arylation products by a factor of 1.5 to 3. Below are given the yields of 2,5-diaryltetrazoles IIId-IIIg obtained in microwave-assisted reaction and under conventional heating, respectively, %: IIId, 55, 40; IIIe, 77, 40; IIIf, 67, 40; IIIg, 60, 21. High yields of the arylation products under microwave activation made it possible to simplify the isolation procedure and avoid additional purification. Thus microwave-assisted arylation of 5-aryltetrazoles with 4-nitrofluorobenzene in DMSO in the presence of sodium hydroxide may be regarded as one of the simplest and effective procedures for the synthesis of 2,5-diaryltetrazoles.The arylation of 5-methyl-, 5-benzyl-, and 5-(4-chlorobenzyl)tetrazoles in all cases afforded mixtures of isomeric 1-and 2-aryl-5-alkyltetrazoles. The ratio of isomeric tetrazoles IIa : IIIa was 2 : 3, and the R = Me (a), PhCH 2 (b), 4-ClC 6 H 4 CH 2

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Arylation of Tetrazolide With Diaryliodonium Halides: Evidence for Intermediacy of Benzyne

Abstract: By the reaction with sodium 5-phenyltetrazolides (II) di-p-tolyliodonium bromide (I) afforded 1-m-tolyl-(III), 2-m-tolyl-5-phenyltetrazole (IV), t-butyl m-tolyl ether (V) together with corresponding p-isomers. This result infers the existence of the pathway through a benzyne.

Cited by 41 publications

References 5 publications

The Discovery and Development of Metal-Free Arylation Reactions with Unsymmetrical Diaryliodonium Salts

The Discovery and Development of Metal-Free Arylation Reactions with Unsymmetrical Diaryliodonium Salts

Iodonium Salts as Benzyne Precursors

Microwave-assisted arylation of 5-substituted tetrazoles

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