Calcium phosphate-vanadate apatite (CPVAP)-catalyzed aerobic oxidation of propargylic alcohols with molecular oxygen

Calcium phosphate-vanadate apatite (CPVAP) works effectively as a catalyst for the aerobic oxidation of propargylic alcohols to the corresponding carbonyl compounds under an atmospheric pressure of molecular oxygen. Moreover, CPVAP can be readily separated by filtration and reused at least 10 times without appreciable loss of the catalytic activity.     

Cationic rhodium(I)/BINAP complex-catalyzed isomerization of secondary propargylic alcohols to alpha,beta-enones

We have developed a cationic rhodium(I)/BINAP complex-catalyzed isomerization of secondary propargylic alcohols to alpha,beta-enones. The asymmetric variant of this reaction, a kinetic resolution of secondary propargylic alcohols, was also developed with good selectivity. The mechanistic study revealed that the isomerization proceeds through intramolecular 1,3- and 1,2-hydrogen migration pathways. [reaction: see text]     

Polyethylene glycol radical-initiated aerobic propargylic oxidation in dense carbon dioxide

The selective aerobic oxidation of alkynes to correspondingα,β-acetylenic ketones was achieved in polyethylene glycol/dense CO₂/O₂ biphasic system without any catalyst or additive.The effects of reaction parameters,e.g.temperature,CO₂ pressure,PEG molecular weight and loading on the reaction were carefully examined.Moreover,various substrates worked well in the presence of PEG 1000 under 5 MPa of CO₂ and 2 MPa of O₂ at 100℃for 12 to 24 h and acceptable yield and selectivity could be obtained in most cases.Preliminary mechanistic investigations were also discussed.     

Na-promoted aerobic oxidation of alcohols to ketones

Aerobic oxidation of a number of diaryl and arylalkyl carbinols to ketones was promoted by Na in THF at room temperature with up to 99% yield. This new oxidation method is also selective with good efficiency for the oxidation of benzylic secondary alcohols but not for a primary alcohol or nonbenzylic secondary alcohols. Under nitrogen, a catalytic amount of Ni or transition metal halides such as CoCl₃, FeCl₃, and NiCl₃ in combination with Na was also found to conduct a dehydrogenation of a secondary alcohol to the corresponding ketone in high yield at room temperature.     

Biomimetic aerobic oxidation of amino alcohols to lactams

The right path: N-Protected amino alcohols undergo aerobic and biomimetic oxidation to the corresponding lactams in the presence of a ruthenium catalyst and a combination of electron-transfer mediators under air. The reaction was used for the synthesis of five-, six-, and seven-, membered lactams and showed good tolerance to a number of N-protecting groups.     

Cesium hydroxide-promoted aerobic oxidation of sec-aromatic alcohols

A CsOH-promoted aerobic oxidation of sec-aromatic alcohols has been developed, using air as a free and clean oxidant, and providing aryl ketones in good to excellent yields.     

Heterocycle-substituted tetrazole ligands for copper-catalysed aerobic oxidation of alcohols

An efficient copper-catalysed aerobic oxidation of alcohols has been established, which employed heterocycle-substituted tetrazoles as ligands. The commercially available (S)-5-(pyrrolidin-2-yl)-1H-tetrazole proved as the best ligand for this oxidation. Under optimized conditions, the substrate scope was broadened. A plausible mechanism was also proposed.     

An oxidovanadium(IV) complex having a perrhenato ligand: An efficient catalyst for aerobic oxidation reactions of benzylic and propargylic alcohols

An oxidovanadium(IV) complex having a perrhenato ligand [VO(ReO₄)(4,4′-^tBubpy)₂][0.25SO₄·0.5ReO₄] (4,4′-^tBubpy = 4,4′-di-tert-butyl-2,2′-bipyridine) efficiently catalyzes not only dehydrogenative oxidation of benzylic and propargylic mono-alcohols but also oxidative CC bond cleavage of meso-1,2-diaryl-1,2-ethanediols under atmospheric molecular oxygen, affording the corresponding carbonyl compounds in good yield.     

Unique gold chemoselectivity for the aerobic oxidation of allylic alcohols

Gold nanoparticles supported on nanocrystalline ceria has been found to be more active and chemoselective than palladium and gold(core)-palladium(shell) nanoparticles for the aerobic oxidation of allylic alcohols.     

Promoting gold nanocatalysts in solvent-free selective aerobic oxidation of alcohols

A trace amount of metal carbonate, acetate or borate significantly boosts gold nanocatalysts in selective aerobic oxidation of alcohols under mild solvent-free conditions.     

Binuclear complexes for aerobic oxidation of primary alcohols and carbohydrates

The influence of electron-donating and electron-accepting properties of three pentadentate ligands was determined in connection with the aerobic oxidation ability of the corresponding binuclear copper(II) complexes for benzyl and allyl alcohols; additionally, the catalytic performance of their palladium and platinum analogs was characterized under comparable conditions. Quantitative aerobic oxidation of benzyl alcohol at 40 °C was achieved with a binuclear copper(II) complex—TEMPO catalyst in 2.5 h, while the regioselective aerobic oxidation of underivatized methyl-β-d-glucopyranoside was accomplished in about 35% yield at 60 °C after 24 h.     

pH-Sensitive gold nanoparticle catalysts for the aerobic oxidation of alcohols

Gold nanoparticles (NPs) stabilized by carboxylate modified polyvinylpyrrolidone have been prepared and fully characterized. The gold NPs efficiently catalyze the aerobic oxidation of benzyl alcohol in water at ambient temperature and are easily separated from the reaction mixture by lowering the pH of the solution, causing the NPs to precipitate. The mechanism of the precipitation process has been studied. Due to the efficiency of this process, the NPs may be reused as catalysts by readjusting their pH.     

A convenient palladium-catalyzed aerobic oxidation of alcohols at room temperature

A simple Pd-catalyzed aerobic oxidation of benzylic and aliphatic alcohols to the corresponding aldehydes and ketones at room temperature is described.     

Recent advances in the homogeneous palladium-catalyzed aerobic oxidation of alcohols

The use of palladium catalysts for the oxidation of alcohols to aldehydes and ketones in the presence of various types of reoxidants is well known. Recently, the advantages of using molecular oxygen as the oxidant in the Pd-catalyzed oxidation of alcohols have been explored. The aim of this review is to provide an overview on the most important homogeneous palladium-catalyzed aerobic oxidation of alcohols without a co-catalyst during last decade until the end of 2007.