Hypervalent iodine compound

A few years later,3 it was shown that o-iodoxybenzoic acid (36)—itself a precursor in the preparation of Dess-Martin periodinane—is able to oxidize very effectively alcohols in DMSO solution. o-Iodoxybenzoic acid—normally referred to as IBX—exists mainly as a cyclic form 37, which crystallizes as a polymer with very low solubility in most solvents with the exception of DMSO. Although, IBX (36) was already known in 1893,4 this ultracentenial reagent found very little use till very recently, when awareness about its solubility in DMSO was raised. 

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Haloalkynes (R—C=C—X) react with ArSnBu3 and Cul to give R—C= C—Ar. Acetylene reacts with two equivalents of iodobenzene, in the presence of a palladium catalyst and Cul, to give 1,2-diphenylethyne. 1-Trialkylsilyl alkynes react with 1-haloalkynes, in the presence of a CuCl catalyst, to give diynes and with aryl triflates to give 1-aryl alkynes. Alkynes couple with alkyl halides in the presence of Sml2/Sm. Alkynes react with hypervalent iodine compounds " and with reactive alkanes such as adamantane in the presence of AIBN. ... 

Varvoglis A (2003) Preparation of Hypervalent Iodine Compounds. 224 69-98 Verkade JG (2003) P(RNCH2CH2)3N Very Strong Non-ionic Bases Useful in Organic Synthesis. 223 1-44... 

The tetrahydrofuranylation of alcohols with hypervalent iodine compounds is described in [479]. 

Varma and coworkers have explored the use of hypervalent iodine compounds on solid support for the first time and developed a facile oxidative procedure that rapidly converts alcohols to the corresponding carbonyl compounds using alumina-sup-ported IBD under solvent-free conditions and MW irradiation in almost quantitative yields [108]. The use of alumina as a support improved the yields markedly as compared to neat IBD (Scheme 6.33). 1,2-Benzenedimethanol, under these conditions, undergoes cyclization to afford l(3H)-isobenzofuranone. 

Diimide from hydrazine hydrate Diimide can be generated from hydrazine hydrate by oxidation with this hypervalent iodine compound in CH2C12. 

Varret F, Boukheddaden K, Codjovi E, Enachescu C, Linares J (2004) On the Competition Between Relaxation and Photoexcitations in Spin Crossover Solids under Continuous Irradiation. 234 199-229 Varret F, see Bousseksou A (2004) 235 65-84 Varret F, see Tuchagues J-P (2004) 235 85-103 Varshney DB, see MacGiUivray LR (2005) 248 201-221 Varvoglis A (2003) Preparation of Hypervalent Iodine Compounds. 224 69-98 Vega S, see Vinogradov E (2005) 246 33-90... 

H347). The reaction of Gilman s reagent, R2CuLi, also involves ligand coupling. There are many examples of hypervalent iodine compounds. 

Other Hypervalent Iodine Compounds Used for Oxidation... 

The fluorine-containing hypervalent iodine compound 47, first described by Dess and Martin,5 finds occasional use in the oxidation of alcohols and is described in some substrates as superior than Dess-Martin periodinane.111... 

Compound 48 is described as a hypervalent iodine compound possessing the distinctive advantages of being air-stable, non-explosive and soluble in common organic solvents.112... 

In recent years hypervalent iodine compounds have been extensively investigated yielding many results of practical synthetic importance. Iodi-nane reagents [e.g., iodoso or iodine(III)] have been prepared in a supported fashion by several groups, mainly as the bis-acetoxy-iodoso derivative28-30 or as the respective dihalogeno compounds.31 Iodoso reagents are employed in the oxidation of hydroquinones as well as phenols, and have been exploited in the formation of spiroketals from various tyrosines. 

The AuCl-catalysed 4 + 2-cycloaddition of benzyne with o-alkynyl(oxo)benzenes produced anthracene derivatives having a ketone in the 9-position, in good to high yields under mild conditions.118 Hypervalent iodine compounds, [5-acyl-2-(trimethyl-silyl)]iodonium triflates, readily yielded acylbenzynes which could be trapped with furan.119 Both DMAD and benzyne reacted with borabenzene to yield substituted borabarrelenes and borabenzobarrelenes, respectively.120... 

V. V. Zhdankin, in his chapter, summarizes the use of hypervalent iodine reagents for carbon-carbon bond formations. The generation of radicals with hypervalent iodine compounds is used in decarboxylative alkylations of organic substrates, whereas phenols and phenol ethers seem to be ideal substrates for... 

All synthetically useful methods for the preparation of a multitude of hypervalent iodine compounds are discussed, with an emphasis on those methods developed over the last decade. In addition, special approaches of mechanistic interest and others suitable for the synthesis of individual compounds of interest are also briefly mentioned. 

A multitude of hypervalent iodine compounds belonging to a range of types have been prepared over the years since 1914, when Willgerodt s book summarised the state of the art in the field [1]. Their number, some 40 years later, was 426, as catalogued by Beringer and Gindler [2]. Presently, hypervalent iodine compounds are too numerous to count, but most of them belong to well-defined families for most of them reliable methods of preparation have been developed. An exhaustive presentation of preparative ways for many individual compounds appeared in 1992 [3], whereas selected methods of preparative value are also available [4]. 

Once formed, hypervalent iodine compounds, i.e. A3- and A5-iodanes, can exchange readily their ligands with nucleophiles, sometimes with assistance from electrophiles. When only nucleophiles are involved, reactions follow an associative pathway, in which an iodate(III) or (V) species is formed. The mixed iodane initially formed is sometimes isolable but usually this procedure takes place with both ligands so that eventually the new species has two... 

This chapter presents methods of preparation for hypervalent iodine compounds with an emphasis on those which serve as reagents. In order to facilitate classification the families of compounds have been divided according to the type of bonds attached to iodine. Procedures described in Organic Syntheses will be only briefly mentioned. 

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