Oxidation Of Allylic Alcohols Research Articles

Selective Oxidation of Benzylic and Allylic Alcohols Using Strontium Manganate in the Presence of Lewis Acids in Solution and under Solvent-Free Conditions

have been usedfor the oxidation of organic compounds. Unfortunately,some of these reagents suffer at least from one of thefollowing disadvantages; cost of preparation, instability,long reaction time, powerful oxidant without selectivity, anddangerous procedures for their preparation. On the otherhand, little attention has been paid to the oxidation proper-ties of manganates and only a few reports are available in theliterature.

Oxidation of allylic alcohols, amines, and sulfides mediated by assembled triphase catalyst of phosphotungstate and non-cross-linked amphiphilic copolymer

A novel catalyst PWAA, an assembled complex of phosphotungstic acid (H 3PW 12O 40) and a non-cross-linked copolymer of N-isopropylacrylamide with an ammonium, was developed. It is an amphiphilic, cross-linked, and supramolecular insoluble complex and showed catalytic activity on oxidation with aqueous hydrogen peroxide. PWAA, used in 2.7×10 −5–2.0×10 −3 mol equiv., catalyzed oxidation of allylic alcohols, amines, and sulfides efficiently. The turnover number (TON) of PWAA reached up to 35,000. PWAA showed a good stability in organic/aqueous media and was reused three to five times.

Solvent‐Free Oxidation of Alcohols by t‐Butyl Hydroperoxide Catalyzed by Water‐Soluble Copper Complex.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Hydrogention and Oxidation of Allyl Alcohol in the Presence of Colloid Palladium In Situ

Kinetic regularities of hydrogenation, oxidation with oxygen, and condensation of allyl alcohol in the presence of colloid palladium in situ were revealed. A mechanism of the reactions was proposed.

Solvent-free oxidation of alcohols by t-butyl hydroperoxide catalyzed by water-soluble copper complex

The catalytic system composed of CuCl 2 and 2,2′-biquinoline-4,4′-dicarboxylic acid dipotassium salt (BQC), was found to be highly efficient for the selective oxidation of secondary benzylic, allylic and propargylic alcohols to the corresponding ketones, with aqueous t-butyl hydroperoxide under phase-transfer catalysis conditions. The catalytic system is stable and can be recycled and reused several times without loss of activity.

A Stabilized Formulation of IBX (SIBX) for Safe Oxidation Reactions Including a New Oxidative Demethylation of Phenolic Methyl Aryl Ethers.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A stabilized formulation of IBX (SIBX) for safe oxidation reactions including a new oxidative demethylation of phenolic methyl aryl ethers.

[reaction: see text] SIBX is a nonexplosive formulation of IBX that can be used as a suspension in a variety of standard organic solvents such as refluxing EtOAc and THF to oxidize safely alcohols into aldehydes and ketones. The use of hot THF is limited to the oxidation of allylic and benzylic alcohols. Most yields are comparable to those obtained with IBX or DMP. SIBX can also be used to perform oxygenative demethylation of 2-methoxyarenols into orthoquinones and catechols.

Highly Selective Oxidation of Allylic Alcohols Catalyzed by Monodispersed 8‐Shell Pd Nanoclusters in the Presence of Molecular Oxygen.

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Reactive oxygen species in epoxidation reactions over titanosilicate molecular sieves

In an attempt to rationalize the differences in the catalytic behavior of titanosilicate molecular sieves when using H2O2 (TS-1, TiMCM-41) versus H2+O2 (Pd–TS-1) as oxidant, the Ti(IV)–superoxo and hydroperoxo/peroxo species formed in situ during the oxidation reactions were investigated by electron paramagnetic resonance (EPR) and diffuse reflectance UV–visible spectroscopies. Two types of superoxo species, A and B, were identified in TS-1; only the latter species was detected in TiMCM-41. EPR has provided evidence, for the first time, for the in situ generation of similar oxo species in reactions using H2+O2 instead of H2O2. The Ti sites adjacent to Pd ions (in Pd–TS-1) behave differently magnetically than the other Ti ions, generating a greater variety of superoxo species (A′, A″, A, B′, B, and C) and corresponding reaction products. Pd enhances the reducibility of Ti and promotes formation of these oxo species at lower temperatures (∼323 K). The epoxide selectivity in the oxidation of allyl alcohol over Pd–TS-1 is higher when using (H2+O2) than when using H2O2. In all cases, type A species predominantly catalyze epoxidations while type B favor the hydroxylations. The selectivity for epoxidation (vis-à-vis allylic oxidation) over these catalysts can be enhanced by controlling the type of Ti–oxo species formed in situ during the oxidation process by a suitable combination of catalyst, oxidant, solvent, and temperature.

Highly selective oxidation of allylic alcohols catalysed by monodispersed 8-shell Pd nanoclusters in the presence of molecular oxygen

Treatment of Pd4phen2(CO)2(OAc)4 with metal nitrates such as Cu(NO3)2 produced monodispersed Pd nanoclusters with a mean diameter and standard deviation (d±σ) of 38±2.1 A (σ/d=6%). The Pd nanoclusters act as heterogeneous catalysts for the selective oxidation of primary aromatic allylic alcohols using molecular oxygen as an oxidant. This unique catalysis can be ascribed to multiple interactions between the alcohol and specific ensemble sites consisting of Pd0, Pd+, and Pd2+ on the cluster surface.

ChemInform Abstract: Practical Os/Cu‐Cocatalyzed Air Oxidation of Allyl and Benzyl Alcohols at Room Temperature and Atmospheric Pressure.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Chromium‐Catalyzed Oxidation of (Homo‐)Allylic and (Homo‐)Propargylic Alcohols with Sodium Periodate to Ketones or Carboxylic Acids.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Asymmetric Sulfoxidation of an Aryl Ethyl Sulfide: Modification of Kagan Procedure to Provide a Viable Manufacturing Process

The asymmetric sulfoxidation of an aryl ethyl sulfide in high enantioselectivity was required as part of a manufacturing route to a candidate drug (ZD3638) within AstraZeneca Pharmaceuticals. The initial discovery process provided small quantities of the required material to satisfy early toxicological work. The optimisation of this sulfoxidation process was required to improve enantioselectivity and therefore yield, and also to improve robustness for manufacturing routinely. Previous studies had indicated that asymmetric sulfoxidation of an aryl ethyl sulfide proceeded with moderate enantioselectivity. Initially, Sharpless conditions which are used for the oxidation of allylic alcohols were employed to effect sulfoxidation in 60% ee; this system was then studied extensively to provide new conditions in 80% ee. Finally, the use of factorial experimental design to explore key parameters in the catalyst formation for these conditions was then studied. This showed the equivalents of the titanium (IV) isopropoxide (0.95 equiv) and (−)-d-diethyl-d-tartrate (1.45 equiv) to be essential factors in controlling enantioselectivity; this has resulted in a viable process with 92% ee in solution, which is improved to greater than 99% ee in the subsequent work-up.

Copper-catalysed aerobic oxidation of alcohols using fluorous biphasic catalysis

A copper(I) catalysed and TEMPO mediated fluorous biphasic oxidation of primary, secondary, allylic and benzylic alcohols with oxygen in the presence of a bipyridine ligand bearing perfluorinated ponytails is described. High chemoselectivities are observed in the oxidation of substituted cyclohexanols (substituted axial cyclohexanols react 6–8 times faster than the corresponding equatorial cyclohexanols).

Practical Os/Cu-cocatalyzed air oxidation of allyl and benzyl alcohols at room temperature and atmospheric pressure.

[reaction: see text] A new protocol for the oxidation of primary and secondary allyl and benzyl alcohols at room temperature and using 1 atm of air is described. The procedure uses low loadings of copper salts and osmium tetroxide, which is activated with quinuclidine and prereduced with an alkene. Chemoselectivity for allyl and benzyl alcohols is very high, no overoxidation is observed, and the reaction takes place under neutral conditions.

Selective oxidations of allylic alcohols with H 2O 2 on a series of lanthanide decatungstate modified with 1-hexadecylpyridinium cation [{C 5H 5N(CH 2) 15CH 3} 7H 2Ln(III)W 10O 36; cetyl-LnW10, Ln: La–Er]: kinetic features and working mechanisms

Selective oxidation of 1-octen-3-ol to 1,2-epoxy-3-octanol and 1-octen-3-on with H 2O 2 catalyzed by {C 5H 5N(CH 2) 15CH 3} 7H 2Ho(III)W 10O 36(cetyl-HoW10) in a CHCl 3–H 2O 2 aqueous biphasic system, adapted as a test catalytic reaction, was kinetically investigated. The rate equations for the epoxide and enon formation were successfully described by equations: R epoxy= k 1,epoxy[substrate][H 2O 2] 1.6, and R enon= k 1,enon[substrate][H 2O 2] −0.6. A working mechanism in which H 2O 2 molecule acts additionally to the substrate molecule which has been activated by interaction with a peroxo-species formed on the cetyl-LnW10 catalyst was proposed; the H 2O 2 molecule promotes the epoxide formation, but suppresses the enon formation. 2-Hexen-1-ol was easily oxidized in the catalyst system, although 2-octene without a terminal OH-group was not. Moreover, the activity decreased drastically as the olefinic-group was far away from the terminal position. These results indicate that the terminal OH-group plays an important role in the activation of the substrates. The working state and the activity of catalyst were greatly influenced by the polarity of the solvent used. Especially, in the organic solvent-free system, the activity was very much promoted. Thus, cetyl-LnW10 is a suitable catalyst, from the environmental viewpoint. With the oxidations of both 1-octen-3-ol and 2-hexen-1-ol catalyzed by a series of Ln(III)W10; Ln: La–Er, the activities varied regularly according to the tendency of contraction of the Ln(III) ion. Those findings were interpreted reasonably by the mode of interaction and the working mechanism postulated, and clearly support the proposal that the 4f n -electrons of the Ln(III) ion participate in the catalysis.

Role of Epoxides in the Oxidation of Allyl Alcohol, Allyl Formate, and Allyl Acetate in Acetic Acid

The formation of epoxy derivatives as intermediate products in the oxidation of allyl alcohol, allylformate, allyl acetate in acetic acid was proved. Intermediate epoxy compounds undergo further trans-formations: They react with acetic acid to give glycerol esters or are converted into polyethers of glyceroland its esters. The rate constants for transformations of 2,3-epoxypropanol, 2,3-epoxypropyl formate, and 2,3-epoxypropyl acetate along these pathways were measured. Higher selectivity of glycerol ester formation from allyl formate was substantiated.

Dirhodium(II) carboxylate-catalysed oxidation of allylic and benzylic alcohols

Allylic and benzylic alcohols are oxidised to the corresponding carbonyl compounds using tert-butyl hydroperoxide, preferably in stoichiometric amounts, and dirhodium(II) tetraacetate as catalyst (1 mol%) in dichloromethane at ambient temperature.

Kinetics and mechanism of ruthenium(III)-catalysed oxidation of allyl alcohol by acid bromate-autocatalysis in catalysis

The kinetics of oxidation of CH2=CHCH2OH with KBrO3 in the presence of RuIII catalyst in aqueous acid medium has been studied under varying conditions. The active species of oxidant and catalyst were HBrO3 and [Ru(H2O)6]3+ respectively. The autocatalysis exhibited by one of the products, i.e., Br−, was attributed to the formation of a complex between the bromide ion and RuIII. A composite scheme and rate law were proposed. Reaction constants involved in the mechanism have been evaluated.

Oxidation of aryl-substituted allylic alcohols by an optically active Fe(III)(porph*) catalyst: enantioselectivity, diastereoselectivity and chemoselectivity in the epoxide versus enone formation

A set of aryl-substituted allylic alcohols (±)- 2 was oxidized using the chiral Fe(porph*) complex 1 as the catalyst and iodosyl benzene (PhIO) as the oxygen source. Whereas one enantiomer of the allylic alcohol 2 is preferentially epoxidized to give the threo- or cis-epoxy alcohol 3 (up to 43% e.e.) as the main product (d.r. up to >95:5), the other enantiomer of 2 is enriched (up to 31% e.e.). Some non-stereoselective allylic oxidation to give the enone 4 also takes place. The observed diastereo- and enantioselectivities in the epoxidation reactions are rationalized in terms of a synergistic interplay between the hydroxy-directing effect and the steric interactions of the catalyst 1 and the substrate 2.