Macroporous polystyrene-supported IBX amide: the improved oxidative properties in various solvents

In this study, macroporous polystyrene-supported IBX (MPS-IBX) amides were prepared in two simple steps, and the polymeric reagent was then evaluated for its efficiency in converting a range of alcohols to the corresponding carbonyl compounds in various solvents. The results indicated that the MPS-IBX amides were compatible with a variety of solvents, and had a more efficient oxidation activity toward alkyl alcohols than the gel type polystyrene-supported IBX amides. Finally, the resin that was consumed in the oxidation reaction was regenerated to give a restored loading level of 0.44-0.54 mmol/g.     

A facile route to a polymer-supported IBX reagent

A three-step preparation of a polymer-supported IBX reagent from poly(p-methylstyrene) is reported. This reagent has been used successfully for the efficient oxidation of a series of alcohols to the corresponding aldehydes.     

A novel and efficient synthesis of DOPA and DOPA peptides by oxidation of tyrosine residues with IBX

An efficient route to 3,4-dihydroxylphenylalanine (DOPA) and DOPA peptides was described by oxidation of l-tyrosine and l-tyrosine derivatives with 2-iodoxybenzoic acid (IBX). DOPA was obtained after an situ reduction of the corresponding ortho-quinone with sodium dithionite. Oxidation reactions proceeded in good yields and high chemo- and regio-selectivity. The chirality of the DOPA residue was retained under the reaction conditions. The efficiency and the selectivity of the reaction were successfully tested using recyclable polymer-supported IBX.     

IBX/n-Bu4NBr/CH2Cl2-H2O: a new mild system for selective oxidation of secondary alcohols

A new alternative system for the chemoselective oxidation of secondary hydroxyl group to ketone with IBX/n-Bu₄NBr in CH₂Cl₂-H₂O has been developed. Under the reaction conditions, the secondary hydroxyl group was highly chemoselectively oxidized to the corresponding ketone, in moderate to good yields at rt, in the presence of primary hydroxyl group within the same molecule.     

Simple preparation of polymer supported IBX esters and amides and their oxidative properties

Novel polymer supported IBX esters and amides were prepared in two steps, which were the coupling of 2-iodobenzoic acid to a hydroxy or amino polystyrene followed by activation of the intermediate product. These polymer supported reagents were tested as oxidants by the conversion of a series of alcohols to the corresponding aldehydes or ketones. We found that the polymer supported IBX amides displayed excellent oxidative activity, in that they oxidized benzyl alcohol to benzaldehyde completely within 1 h at an oxidant to alcohol ratio of 2 to 1.     

Methane chemical ionization mass spectrometry of flavonoids

The chemical ionization mass spectra of a representative selection of flavones, flavonols, flavanones, and flavanols have been examined, using methane as the reagent gas. The flavones and flavonols showed no significant fragmentation under the conditions employed, but the flavanones and flavanols showed characteristic fragmentation which could be of use in structural elucidation of these compounds.     

A novel use of the recyclable polymer-supported IBX: an efficient chemoselective and regioselective oxidation of phenolic compounds. The case of hydroxytyrosol derivatives.

A useful and novel application of polymer-supported IBX for the chemoselective and regioselective oxidation of phenolic compounds has been described. Hydroxytyrosol and carboxymethylated hydroxytyrosol have been prepared in good conversions and yields under green chemistry conditions in the presence of dimethyl carbonate as the solvent. Polymer-supported reagent has been recovered by simple filtration, regenerated and reused for more cycles of oxidation reactions without loss of efficiency.     

Studies on oxidations with IBX: oxidation of alcohols and aldehydes under solvent-free conditions

A variety of allylic and benzylic alcohols are oxidized to their respective carbonyl compounds with IBX under solvent-free conditions at ca. 60-70 °C. It has also been found that some of the aromatic aldehydes also undergo oxidation when heated with IBX at 90 °C under solvent-free conditions; notably, this transformation does not occur under the otherwise identical but heterogeneous conditions.     

IBX in an ionic liquid: eco-friendly oxidation of 17α-methylandrostan-3β,17β-diol, an intermediate in the synthesis of anabolic oxandrolone

An easily available hypervalent iodine(V) reagent, 2-iodoxybenzoic acid (IBX) immobilized in the ionic liquid [bmim][Br] was found to be an efficient and eco-friendly protocol for the oxidation of 17α-methylandrostan-3β,17β-diol (1). At ambient temperature oxidation of 1 with IBX gave mestanolone (2) in good yield and with an increased stoichiometric amount of IBX, oxidation adjacent to the carbonyl functionality (α,β-unsaturation) occurred to give dehydrogenated 17β-hydroxy-17α-methyl-Δ¹-androsten-3-one (3) as the major product in a one-pot reaction. The product is easily obtained by extraction with diethyl ether and evaporation of the solvent.     

2-碘酰基苯甲酸(2-Iodoxybenzoic acid, IBX)在有机合成中的应用

综述了近年来2-碘酰基苯甲酸(2-iodoxybenzoic acid, IBX)在有机合成中的应用, 重点评述了IBX对醇类、含氮有机物、含硫有机物、连接在芳环上的碳原子的氧化反应, 探讨了IBX在α,β-不饱和羰基化合物和内酯合成中的应用, 这些反应具有反应条件温和、产率高、选择性好等优点. 简单介绍了IBX的一些新衍生物的合成及应用.     

Direct synthesis of carbonyl compounds from THP ethers with IBX in the presence of β-cyclodextrin in water

Water, an environmentally friendly reaction medium, has been utilized for the oxidative deprotection of tetrahydropyranyl ethers 1 with IBX at room temperature in the presence of β-cyclodextrin to give the corresponding carbonyl compounds 2.     

o-Iodoxybenzoic acid (IBX): a versatile reagent for the synthesis of N-substituted pyrroles mediated by β-cyclodextrin in water

o-Iodoxybenzoic acid (IBX), a very mild and efficient hypervalent iodine(V) reagent, aromatizes diversely substituted 1-benzylpyrrolidines and N-substituted l-proline analogues to the corresponding substituted pyrroles in good to excellent yields under mild conditions mediated by β-cyclodextrin in water at room temperature. To the best of our knowledge, this is the first report on IBX, promoting complete aromatization leading to N-benzylpyrroles from the corresponding saturated five membered heterocyclic derivatives in water medium.     

Silica gel supported InBr3 and InCl3: new catalysts for the facile and rapid oxidation of 2′-hydroxychalcones and flavanones to their corresponding flavones under solvent free conditions

Silica gel supported InBr₃ or InCl₃ (15-20 mol %) were explored as a new solid-support catalysts for the facile and efficient oxidation, under solvent free conditions, of 2′-hydroxychalcones and flavanones to yield the corresponding flavones in >80% yield. The catalysts are easily prepared, stable, and efficient under mild reaction conditions.     

Iodine(V) reagents in organic synthesis. Part 4. o-Iodoxybenzoic acid as a chemospecific tool for single electron transfer-based oxidation processes

o-Iodoxybenzoic acid (IBX), a readily available hypervalent iodine(V) reagent, was found to be highly effective in carrying out oxidations adjacent to carbonyl functionalities (to form alpha,beta-unsaturated carbonyl compounds) and at benzylic and related carbon centers (to form conjugated aromatic carbonyl systems). Mechanistic investigations led to the conclusion that these new reactions are initiated by single electron transfer (SET) from the substrate to IBX to form a radical cation which reacts further to give the final products. Fine-tuning of the reaction conditions allowed remarkably selective transformations within multifunctional substrates, elevating the status of this reagent to that of a highly useful and chemoselective oxidant.     

2-碘酰基苯甲酸在有机合成中的研究与应用

高价有机碘化合物的反应性质与过渡金属相似,其参与的反应具有反应条件较温和、选择性好、产率高及环境友好等优点,因而近年来关于高价有机碘试剂的研究受到广泛关注,在有机合成领域中获得了较多应用.综述了近年来高价有机碘试剂2-碘酰基苯基酸(IBX)在有机合成中的研究及应用,包括IBX在氧化羟基、含氮化合物和含硫化合物,在制备α...     

Mild oxidation of alcohols with O-iodoxybenzoic acid (IBX) in ionic liquid 1-butyl-3-methyl-imidazolium chloride and water

[reaction: see text] A mild, efficient, and eco-friendly procedure for the oxidation of alcohols with IBX in ionic liquid [bmim]Cl and water has been developed. Simply stirring of a solution of the alcohol and IBX in [bmim]Cl/water at room temperature followed by extraction with ether or ethyl acetate and removal of the solvent gives excellent yields of the corresponding carbonyl compounds. Recycling and reuse of the oxidant and ionic liquid have also been reported.     

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.     

Analysis of antioxidant compounds in sweet orange peel by HPLC-diode array detection-electrospray ionization mass spectrometry

HPLC-diode array detection-electrospray ionization mass spectrometry was used to determine qualitatively and quantitatively the flavonoid content of several fractions and residues of extracts of Greek navel sweet orange peel (Citrus sinensis) from the region of southern Greece (Leonidi-Tripoli). The main groups of flavonoids found according to HPLC retention times, spectral data and literature references were polymethoxylated flavones, C-glycosylated flavones, O-glycosylated flavones, O-glycosylated flavanones, flavonols and phenolic acids and their derivatives. The ethyl acetate fraction which has been shown in previous work to possess the best radical scavenging activity among the others was found to contain C-glycosylated flavones, polymethoxylated flavones, O-glycosylated flavones, O-glycosylated flavanones, two phenolic acid derivatives and two unknown compounds, all in low concentrations. The group of C-glycosylated flavones was reported for the first time in the peel of Navel sweet orange. The C-glycosylated flavones found according to their spectral characteristics and literature were 6-C-beta-glucosyldiosmin, 6,8-di-C-glucopyranosylapigenin, 6,8-di-C-beta-glucosyldiosmin and two unknown. The results suggest that the ethyl acetate fraction of navel Citrus sinensis peel consists of significant antioxidant compounds and can be used as a food additive of natural origin or a pharmaceutical supplement using as a source of peel the byproducts of the orange juice industry.     

Facile synthesis of isatins by direct oxidation of indoles and 3-iodoindoles using NIS/IBX

A facile one-pot access to a broad range of isatins by direct oxidation of indoles using NIS/IBX reagent in DMSO at 25?°C in very good isolated yields is reported. It is shown by mechanistic investigations that a number of substituted indoles react rapidly with NIS in DMSO to produce intermediary 3-iodoindoles, which undergo oxidation subsequently to isatins with IBX.     

IBX,an Excellent Reagent for Oxidation of 2-Furyl Carbinols: A New and General Method for Preparation of Furyl Ketones

An excellent method for the oxidation of various 2-furyl carbinols with o-iodoxybenzoic acid (IBX) has been described. This method provides a simple and efficient route to a variety of 2-furylketones which are not readily accessible otherwise.