Hypervalent iodine(V) mediated mild and convenient synthesis of substituted 2-amino-1,3,4-oxadiazoles

A simple protocol for the synthesis of 2-amino-1,3,4-oxadiazoles starting from the corresponding acylhydrazides by cyclodesulfurization of intermediate acylthiosemicarbazides mediated by o-iodoxybenzoic acid in good yields has been described. The protocol is mild with wide substrate scope, and thus a range of 2-amino-1,3,4-oxadiazoles have been prepared.     

A new useful entry of IBX: the synthesis and structure of α-(2-iodobenzoyloxy)ketones

α-Functionalized ketones can be conveniently prepared in one step by the reaction of ketones possessing α-methene with o-iodoxybenzoic acid (IBX) in the presence of potassium iodide. Methyl aryl ketones produced bi-substituted products, whereas the others gave mono-substituted ones.     

Zefirov's reagent and related hypervalent iodine triflates

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A mild oxidative method for the preparation of γ-hydroxy-α-nitroolefins from α,β-epoxyketoximes using IBX

An efficient method for the preparation of γ-hydroxy-α-nitroolefins from α,β-epoxyketoximes has been developed using IBX. The reaction occurs at room temperature without the formation of over-oxidation products and also has an easy work-up procedure.     

Arylation of anilines: formation of diarylamines using diaryliodonium salts

Extensive studies on the reaction of the fluoride ion with diaryliodonium salts demonstrated that this is a generic process for the formation of fluoroarenes and has particular advantages for the preparation of fluorine-18 radiopharmaceuticals. During these studies it became apparent that nucleophiles other than the fluoride ion may be employed for generating substituted aromatics. This approach can be applied, using substituted anilines as the nucleophilic reagent, to the formation of a range of diarylamines in good yield. Optimised conditions for the reaction of a diaryliodonium salt with an aniline utilise TFA as the preferred counter-ion in DMF (130 °C, 24 h).     

Oxidative rearrangements of arylalkenes with [hydroxy(tosyloxy)iodo]benzene in 95% methanol: a general, regiospecific synthesis of α-aryl ketones

The treatment of arylalkenes with [hydroxy(tosyloxy)iodo]benzene in 95% methanol affords the corresponding α-aryl ketones. This oxidative rearrangement is general for acyclic and cyclic arylalkenes and permits regioselective syntheses of isomeric α-phenyl ketone pairs.     

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.     

Use of Stang's reagent, PhI(CN)OTf, to promote Pummerer-like oxidative cyclization of 2-(phenylthio)indoles

Treatment of various 2-(phenylthio)indoles, bearing nucleophilic groups tethered to C(3), with PhI(CN)OTf initiated an oxidative cyclization sequence that afforded 3,3-spirocyclic 2-(phenylthio)indolenines or oxindoles in moderate yield.     

Diversification of shotgun process

Three protocols for shotgun process are put forth in which simultaneous multi-fold reactions occur exclusively to each other. The first one involves simple combination of selective and non-selective reactions. Even if the simple protocol fails to give rise to the high selectivity, satisfactory outcome can be achieved by kinetic control or adjustment of functional groups.     

Hypervalent Iodine(III) Sulfonate Reagent Mediated Synthesis of 4‐Aryl‐2‐Phenyloxazoles in Ionic Liquid

A new and efficient method for the synthesis of 4‐aryl‐2‐phenyloxazoles is described which is based upon the reaction of α‐[(2,4‐dinitrobenzene)sulfonyl]oxy ketone intermediates with benzamide in ionic liquid.     

Direct C-H substitution reaction of anilides using hypervalent iodine and their regioselective issues

The direct C-H substitution reactions of anilides using hypervalent iodine proceeded to afford azide, chloro, bromo, and fluoro derivatives, and their regioselectivity were described. In the specific reaction conditions, the unique regioisomers were obtained.     

Access to new 4-fluorocyclohexa-2,5-dienimines using hypervalent iodine and pyridinium polyhydrogen fluoride

Nucleophilic para-fluorination of substituted anilines to afford 4-fluorocyclohexadieneimine derivatives is achieved in the presence of hypervalent iodine and pyridinium polyhydrogen fluoride.     

Iodine(III)-mediated ethoxychlorination of enamides with iron(III) chloride

The combination of (diacetoxyiodo)benzene and iron(III) chloride in ethanol allows the efficient regioselective ethoxychlorination of a broad range of enamides. Mechanistic studies tend to rule out the involvement of free radical species and point towards the implication of a mixed [chloro(ethoxy)iodo]benzene intermediate.     

Synthetic application of water-soluble hypervalent iodine reagents in aqueous media

Along with the vigorous development of hypervalent iodine chemistry, water-soluble hypervalent iodine reagents have received considerable attentions in recent years. In order to obtain water-soluble hypervalent iodine reagents, two strategies have been employed including introduction of hydrophilic functional groups onto the phenyl ring and formation of complex of iodosylbenzene with crown ether. And, it is observed that four kinds of hypervalent iodine reagents exhibit more or less solubility in water including hypervalent iodine reagents containing hydrophilic ligands, diaryliodonium salts, oligomeric iodosylbenzene sulfate, and iodylbenzene and its derivatives. In this review, we summarize these water-soluble hypervalent iodine reagents and their broad synthetic applications in aqueous media.     

Electrophilic (phenylsulfonyl)difluoromethylation of thiols with a hypervalent iodine(III)-CF2SO2Ph reagent

A hypervalent iodine(III)-CF₂SO₂Ph compound (3) has been successfully prepared with selective nucleophilic reaction using PhSO₂CF₂SiMe₃ reagent, and this previously unkown compound 3 was found to act as a new electrophilic (phenylsulfonyl)difluoromethylation reagent for a variety of S-nucleophiles under very mild reaction conditions.     

CeCl3·7H2O/IBX-promoted oxidation of 3-alkylindoles to 3-hydroxyoxindoles

3-Alkylindoles undergo smooth oxidation with IBX in the presence of CeCl₃·7H₂O in aqueous acetonitrile at ambient temperature to afford the corresponding 3-hydroxyoxindoles in high yields. This method is very useful for the direct preparation of 3-hydroxyoxindoles from 3-alkylindoles. Operational simplicity, mild and neutral reaction conditions in aqueous solution are the key features of this protocol.     

Iodofluorination of alkenes and alkynes promoted by iodine and 4-iodotoluene difluoride

It was found that a mixture of molecular iodine and 4-iodotoluene difluoride are useful to generate in situ the couple ‘IF’ that was able to add in a Markovnikov fashion and with prevalent anti-stereoselectivity to various alkenes and alkynes.     

On the regioselectivity of the PIFA-mediated bis(trifluoroacetoxylation) of styrene-type compounds

The addition of the hypervalent iodine reagent PIFA [phenyliodine(III) bis(trifluoroacetate)] to a series of styrene-type compounds results in the bis(trifluoroacetoxylation) of the double bond as two possible 1,2- and 1,1-regioisomers. We found that 1,1-regioisomers resulted to be unstable during chromatographic purification yielding the related arylacetaldehydes. In this paper, we show our efforts to explore the regioselectivity of this reaction, and to rationalize the results with respect to the electronic nature of the corresponding aryl ring through alternative mechanistic pathways.