有机高价碘化合物在合成中的应用

本文综述了有机高价碘化合物在合成中应用的进展, 介绍了有机高价碘化合物的制备, 阐述了有机高价碘化合物作为芳基, 烷基, 烯基, 炔基, 转移剂及芳基碘盐应用于复杂化合物的合成。     

Efficient generation and trapping of acylbenzynes from hypervalent iodine compounds

[5-Acyl-2-(trimethylsilyl)phenyl]iodonium triflates were prepared for the generation of benzynes bearing ketone function. Treatment of the iodonium triflates with Bu₄NF in CH₂Cl₂ in the presence of furan at room temperature gave 6-acyl-1,4-epoxy-1,4-dihydronaphthalenes in high yields. The mild conditions and the tolerance of the ketone function on benzyne generation are attributable to the advantage of hypervalent iodine compounds.     

Recent progress in the electrochemistry of hypervalent iodine compounds

Hypervalent iodine compounds constitute a well-established and broadly used reagent family in organic synthesis. As they are usually either used in stoichiometric quantities or generated in situ from an aryl iodide precursor using a terminal oxidant, the associated waste and separation problems pose major challenges en route to sustainable and scalable processes. In this regard, the use of inexpensive electric current as a traceless oxidant for the in-situ generation of hypervalent iodine has emerged as a promising alternative. This review summarizes the advances over the past 2 years, including improved electrolysis protocols, new synthetic applications, and concepts for enhancing the sustainability of the reactions.     

ortho-Phosphoryl stabilized hypervalent iodosyl- and iodyl-benzene reagents

The synthesis and reactivity of a new IBX analogue (2-iodylphenyl)diphenyl-phosphine oxide 10 is described herein along with its analysis by single crystal X-ray diffraction.     

Electrogenerated hypervalent iodine compounds as mediators in organic synthesis

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Novel 10-I-3 hypervalent iodine-based compounds for electrophilic trifluoromethylation

The synthesis of a new family of 10-I-3 hypervalent iodine compounds is described in which the CF3 functionality participates directly in the hypervalent bond. These materials are accessible by nucleophilic ligand substitution at iodine using Me3SiCF3 in the presence of a substoichiometric amount of fluoride. The expected T-shaped geometry at iodine was verified by X-ray crystallographic analyses of three of the products (1-trifluoromethyl-1,2-benziodoxol-3-(1 H)-one and two substituted 1-trifluoromethyl-1,3-dihydro-1,2-benziodoxoles). Preliminary results for the direct electrophilic transfer of the trifluoromethyl moiety onto organic nucleophiles show modest reactivity in polar aprotic solvents under relatively mild conditions. The overall process can be understood as a formal umpolung of the CF3 group.     

A novel method for the synthesis of 4'-thiopyrimidine nucleosides using hypervalent iodine compounds

The coupling reactions of cyclic sulfides with a silylated pyrimidine nucleobase using a hypervalent iodine reagent were investigated. The reaction of silylated uracil with cyclic sulfide 12 using PhI=O gave the desired beta-anomer 14 in moderate yield. 4'-Thiouridine (22) was obtained by deprotection of 14.     

New chiral hypervalent iodine(V) compounds as stoichiometric oxidants

The synthesis and application of some new hypervalent iodine compounds bearing chiral and achiral ester motives derived from easily accessible starting materials is presented. The oxidation is carried out using dimethyldioxirane as an oxidant providing the desired compounds in moderate to high yields. A crystal structure analysis for one iodine(V) derivative is investigated. The λ⁵-iodanes are applied as stoichiometric reagents in the oxidation of thioanisole to phenylmethyl sulfoxide, benzyl alcohol to benzaldehyde, and meso-hydrobenzoine to benzaldehyde, benzyl, and benzoin.     

Rapid aerobic iodination of arenes mediated by hypervalent iodine in fluorinated solvents

Arenes are rapidly converted to the corresponding iodides by aerobic oxidative iodination at room temperature by treatment with iodine and catalytic quantities of nitrous acid in a fluorinated solvent. Dichloroiodic acid is proposed as the actual iodination reagent.     

Facile iodine(III)-induced oxidative cycloaddition of N-sulfonyl imines with methylene compounds under neutral conditions

An efficient oxidative cycloaddition of N-sulfonyl imines with methylene compounds using PhIO with a catalytic amount of KI under neutral conditions, which affords 2,2-difunctionalized aziridines in good to excellent yields, is reported.     

Promotion effect of hypervalent iodine compounds on the reactions of 3-hydroxy-4-nitrofurazan with cycloalkenes

Russian Chemical Bulletin -     

Transformation of acridines and azepines into the corresponding 3-oxo-heterocycles by means of hypervalent aromatic iodine compounds

Summary The acridines3,5, and6, as well as the dibenzo[b,f]-azepine4 were converted into the 3-oxo-derivatives7–10 using hypervalent iodine compounds (iodosylbenzene and bis-(trifluoroacetoxy)iodopentafluorobenzene).

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Oxidation von Acridinen und Azepinen in ihre 3-Oxoderivate mit Hilfe von hypervalenten aromatischen Jodverbindungen (Kurze Mitt.)

Zusammenfassung Die Acridine3,5 und6 sowie das Dibenzo[b,f]azepin4 wurden mit Hilfe der beiden hypervalenten Jod-Verbindungen Jodosobenzol (1) und Bis-trifluoroacetoxyiodbenzol (2) zu den entsprechenden 3-Acridinonen7,9 und10 sowie zum Dibenzoazepin-3-on8 oxidiert.

     

Metal-free oxidative amide formation with N-hydroxysuccinimide and hypervalent iodine reagents

An oxidative amide formation using N-hydroxysuccinimide and hypervalent iodine reagents was developed. The method enables a wide range of aldehydes and amines to be coupled under mild reaction conditions providing amide in good to excellent yield. The radical species in the reaction mixture was observed for the first time using ESR measurement, and along with other mechanistic investigations, a plausible mechanism of the reaction was proposed.     

Reaction of (diacetoxyiodo)benzene with excess of trifluoromethanesulfonic acid. A convenient route to para-phenylene type hypervalent iodine oligomers

Reaction of (diacetoxyiodo)benzene [PhI(OAc)₂] in trifluoromethanesulfonic acid (TfOH) resulted in oligomerization of PhI(OAc)₂. Quenching with NaBr gave the bromide salts of hypervalent iodine oligomers that were determined by thermolysis with KI to be a para phenylene type of oligomers. Neutralization of the reaction mixture of PhI(OAc)₂ and TfOH with aqueous NaHCO₃ yielded the triflate salts of iodine oligomers. Furthermore, quenching the reaction mixture with aromatic substrates afforded arylated iodine oligomers. These iodine oligomers were found to be 3-4 of the number average degree of polymerization (P_n) by GC analysis of the thermolysis products and ¹H NMR analysis. The major products, trimer and tetramer, were synthesized independently.     

A novel and convenient approach for tosyloxylation of aromatic ring of some ortho-substituted phenolic compounds using [hydroxy(tosyloxy)iodo]benzene

The oxidation of some substituted monohydric phenols, containing electron-withdrawing substituents at the ortho position to the phenolic group, with [hydroxy(tosyloxy)iodo]benzene (HTIB, Koser’s reagent) leads to novel tosyloxylation of aromatic ring, thereby offering a convenient synthesis of hitherto unknown 4-tosyloxy-2-substituted phenols.