Novel System for the Synthesis of Nitriles from Aldehydes Using Aqueous Ammonia and [Bis(Trifluoroacetoxy)iodo]benzene

A simple and mild method for the conversion of varieties of aldehydes to the corresponding nitriles using aqueous ammonia and trivalent hypervalent iodine reagent, [bis(trifluoroacetoxy)iodo]benzene, at room temperature is discussed. Advantages of this system are short reaction time, easy workup, and moderate to good yields.     

Simple and facile method for the preparation of vinyl azides

A synthetic utility of [bis(trifluoroacetoxy)iodo]benzene on α,β-unsaturated carboxylic acid is described. This is the first example of preparation of vinyl azide using α,β-unsaturated carboxylic acids directly by using hypervalent iodine reagent. The advantage of this protocol is characterized with non-toxicity of starting material and shorter reaction times to obtain good preparative yields. The method is also useful for the preparation of acyl azides.     

Ruthenium bis(bipyridine) sulfoxide complexes: new catalysts for alkene epoxidation

The ruthenium bis(bipyridine) sulfoxide complexes Ru-1 and Ru-2 exhibit high catalytic activity for epoxidation of unfunctionalized olefins in the presence of [bis(acetoxy)iodo]benzene; with the chiral catalyst, Ru-2, asymmetric induction up to 94% was observed for beta-methylstyrene.     

Stereoselective synthesis of 5-7 membered cyclic ethers by deiodonative ring-enlargement using hypervalent iodine reagents

Stereoselective synthesis of 5-7 membered cyclic ethers was achieved by deiodonative ring-enlargement of cyclic ethers having an iodoalkyl substituent. The reaction took place readily under mild conditions using hypervalent iodine compounds and an acetoxy or a trifluoroacetoxy group was introduced into the rings depending on the hypervalent iodine reagent employed. The use of hexafluoroisopropanol (HFIP) as solvent is critical.     

Epoxidation of olefins catalyzed by manganese(III) porphyrin in a room temperature ionic liquid

The epoxidation of several alkenes catalyzed by (meso-tetrakis(pentafluorophenyl)porphinato) manganese(III) chloride (MnTFPPCl) was carried out in a 3:1 [bmim]PF₆ ionic liquid/CH₂Cl₂ mixed solvent. The conversion and the yield of epoxide are excellent. It was also found that [bis(acetoxy)iodo]benzene [PhI(OAc)₂] is a more efficient oxidant than PhIO. The catalyst in the ionic liquids can be recycled for several runs without substantial diminution in the catalytic activity.     

Synthesis of novel perfluoroalkyl-containing polyethers

The synthesis of iodo(perfluoroalkyl)epoxides by radical addition of perfluoroalkyl iodides to allyl glycidyl ether and 1,2-epoxydec-9-ene is described. Dehydroiodination of additional products upon treatment with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) gives unsaturated products. The use of Bu₃SnH/Bz₂O₂ as a reduction reagent of iodo(perfluoroalkyl)allyl glycidyl ethers allows to save oxirane ring. Cationic polymerization of saturated or functional (with iodine or double bond) fluoroalkyl oxiranes under action of catalytic amount of BF₃^.Et₂O proceeds only on epoxide group. In case of poly(9-iod-10-(perfluoroalkyl)-1,2-epoxyalkane) iodine atoms are removed by standard zinc reduction.     

Microwave-assisted regioselective synthesis of natural 6-prenylpolyhydroxyisoflavones and their hydrates with hypervalent iodine reagents

Microwave-assisted oxidative rearrangement of 3′-iodotetraalkoxychalcones with hypervalent iodine such as [hydroxy(tosyloxy)iodo]benzene or [bis(trifluoroacetoxy)iodo]benzene, followed by microwave-mediated hydrolysis and in situ cyclization of the resultant acetals gave 6-iodotrialkoxyisoflavones. Pd(0)-catalyzed coupling reaction of the 6-iodoisoflavones with 2-methyl-3-butyn-2-ol under microwave irradiation gave 6-alkynylisoflavones, whose hydrogenation gave the respective hydrates of wighteone, lupisoflavone and derrubone. Wighteone (1a), lupisoflavone (1b) and derrubone (1c) were obtained by dehydration of their respective hydrates under microwave irradiation.     

Metal‐Free CH Bond Activation of Branched Aldehydes with a Hypervalent Iodine(III) Catalyst under Visible‐Light Photolysis: Successful Trapping with Electron‐Deficient Olefins

Direct acyl radical formation of linear aldehydes (RCH₂‐CHO) and subsequent hydroacylation with electron‐deficient olefins can be effected with various types of metal and nonmetal catalysts/reagents. In marked contrast, however, no successful reports on the use of branched aldehydes have been made thus far because of their strong tendency of generating alkyl radicals through the facile decarbonylation of acyl radicals. Here, use of a hypervalent iodine(III) catalyst under visible light photolysis allows a mild way of generating acyl radicals from various branched aldehydes, thereby giving the corresponding hydroacylated products almost exclusively. Another characteristic feature of this approach is the catalytic use of hypervalent iodine(III) reagent, which is a rare example on the generation of radicals in hypervalent iodine chemistry.     

Metal‐Free C?H Bond Activation of Branched Aldehydes with a Hypervalent Iodine(III) Catalyst under Visible‐Light Photolysis: Successful Trapping with Electron‐Deficient Olefins

Direct acyl radical formation of linear aldehydes (RCH₂‐CHO) and subsequent hydroacylation with electron‐deficient olefins can be effected with various types of metal and nonmetal catalysts/reagents. In marked contrast, however, no successful reports on the use of branched aldehydes have been made thus far because of their strong tendency of generating alkyl radicals through the facile decarbonylation of acyl radicals. Here, use of a hypervalent iodine(III) catalyst under visible light photolysis allows a mild way of generating acyl radicals from various branched aldehydes, thereby giving the corresponding hydroacylated products almost exclusively. Another characteristic feature of this approach is the catalytic use of hypervalent iodine(III) reagent, which is a rare example on the generation of radicals in hypervalent iodine chemistry.     

Oxidative rearrangement of alkenes using in situ generated hypervalent iodine(III)

A novel protocol for the oxidative rearrangement of alkenes using in situ generated hypervalent iodine(III) was developed. This approach uses inexpensive, readily available, and stable chemicals (PhI, mCPBA, and TsOH) giving rearrangement products in yields comparable to those obtained using the more expensive commercially available [hydroxy(tosyloxy)iodo]benzene [HTIB or Koser’s reagent]. Additionally, an alternative protocol for the synthesis of 1-methyl-2-tetralone through the one-step epoxidation/rearrangement of 4-methyl-1,2-dihydronaphthalene using mCPBA and TsOH was developed.     

A Convenient Synthesis of 4-(2-Furyl)-2-substituted Thiazoles Utilising [Hydroxy(tosyloxy)iodo]benzene

A facile synthesis of 4-(2-furyl)-2-substituted thiazoles by hypervalent iodine oxidation of 2-acetylfuran (1) using [hydroxy(tosy-loxy)iodo]benzene, followed by treatment of the reaction mixture with appropriate thioureas/thioamides is described.     

Convenient,Solvent-Free Method for Preparation of [Hydroxy(phosphoryloxy)iodo]arenes

A convenient, solvent-free method for preparation of [hydroxy(phosphoryloxy)iodo]arenes is reported. (Diacetoxyiodo)benzene or other hypervalent iodine reagents and phosphates are simply blended and ground for several minutes in an agate mortar, giving good yields of [hydroxy(phosphoryloxy)iodo]arenes with excellent purities.     

2,2,6,6‐Tetramethyl‐1‐piperidinyl‐oxyl/[bis(acetoxy)‐iodo]benzene‐mediated oxidation: A versatile and convenient route to poly(ethylene glycol) aldehyde or carboxylic acid derivatives

A new and very convenient route to oxidized poly(ethylene glycol), with a catalytic nitroxyl radical oxidant (2,2,6,6‐tetramethyl‐1‐piperidinyl‐oxyl) regenerated in situ by stoichiometric amounts of [bis(acetoxy)‐iodo]benzene, is described. Under these conditions, the reaction is quantitative and leads to the pure product by a simple process such as precipitation and washing with diethyl ether. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4022–4024, 2001     

Direct synthesis of bipyrroles using phenyliodine bis(trifluoroacetate) with bromotrimethylsilane

[reaction: see text] The hypervalent iodine(III) reagent, phenyliodine bis(trifluoroacetate) (PIFA), mediates the unprecedented, oxidative coupling reaction of pyrroles to give alpha-linked bipyrroles selectively in the presence of bromotrimethylsilane. This straightforward synthesis could provide 2,3'-bipyrrole by the choice of a N-substituent of pyrrole. Mechanistic consideration of the present reaction is also described.     

Recyclable synthesis of mesityl iodonium(III) salts

An efficient protocol for C–H condensation of hypervalent iodine compounds toward arenes in fluoroalcohols has been applied to the recyclable preparation of mesityl iodonium(III) salts. The electrophilicities of [hydroxy(tosyloxy)iodo]mesitylene (MesI(OH)OTs) and iodomesitylene diacetate (MesI(OAc)₂) are suitably enhanced in 2,2,2-trifluoroethanol. A series of nucleophilic aromatic compounds react smoothly with MesI(OH)OTs and MesI(OAc)₂ or in situ hypervalent iodine(III) species, generated from iodomesitylene, to provide the target mesityl iodonium(III) salts in good yields at room temperature with broad functional group tolerance. This C–H condensation strategy merits high para-regioselectivities during the diaryliodonium(III) salt formation, but the major limitation in the case of low-reactive aromatic substrates is byproduct formation resulting from the self-condensation of the nucleophilic mesitylene ring in MesI(OH)OTs and MesI(OAc)₂.     

Direct, two-step synthetic pathway to novel dibenzo[a,c]phenanthridines

Novel dibenzo[a,c]phenanthridines are prepared regioselectively by the application of a straightforward synthetic pathway, starting from new 3,4-diaryl- and 3,4-dihydro-3,4-diarylisoquinolines prepared via Ritter-type heterocyclization and the more classical two-step reductive amination/Bischler-Napieralski cyclization of triarylethanones, respectively. A comparative study of nonphenolic oxidative coupling methodologies provides a highly efficient procedure, based on the hypervalent iodine reagent phenyliodine(III) bis(trifluoroacetate) (PIFA), to accomplish the final coupling step.     

A versatile PIFA-mediated approach to structurally diverse pyrrolo(benzo)diazepines from linear alkynylamides

The addition of the hypervalent iodine reagent PIFA [phenyliodine(III) bis(trifluoroacetate)] to a series of properly substituted N-(3-aminopropyl)alkynylamides results in the efficient formation of a functionalized 5-aroyl-2-pyrrolidinone skeleton. By proper manipulations of the N(1)-substituents, through consecutive deprotection and/or reductive amination steps, a second cyclization process occurs yielding the target heterocycles. As it will be disclosed, the overall process is open to structural modifications that gives rise to a series of pyrrolo(benzo)diazepine derivatives.     

A new synthesis of dienone lactones using a combination of hypervalent iodine(III) reagent and heteropoly acid

The oxidation of non-phenolic alkanoic acid derivatives to oxygen heterocycles was investigated; a new oxidative route to dienone lactones has been developed using a combination of hypervalent iodine(III) reagent, phenyliodine(III) bis(trifluoroacetate)(PIFA), and heteropoly acid (HPA).     

A novel and efficient oxidative biaryl coupling reaction of phenol ether derivatives using a combination of hypervalent iodine(III) reagent and heteropoly acid

A novel and efficient oxidative biaryl coupling reaction of phenol ether derivatives using a combination of hypervalent iodine(III) reagent, phenyliodine(III) bis(trifluoroacetate) (PIFA), and heteropoly acid has been developed.     

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.