Oxidation Of Secondary Benzylic Alcohols Research Articles

Switching the substrate preference of fungal aryl-alcohol oxidase: towards stereoselective oxidation of secondary benzyl alcohols

Using PELE computational simulations the ability to deracemize secondary benzylic alcohols was introduced (by I500M/F501W double mutation) in stereoselective AAO.

HKUST-1/ABNO-catalyzed aerobic oxidation of secondary benzyl alcohols at room temperature

Efficient heterogeneous Cu-catalyzed aerobic oxidation of benzyl alcohols was discolsed. The combination of HKUST-1 and ABNO exhibited enhanced catalytic activity compare to the previous HKUST-1/TEMPO system in aerobic oxidation of benzyl alcohols. It was observed that the present catalyst was intrinsically heterogeneous and reusable.

Aerobic oxidation of secondary benzyl alcohols catalyzed by phosphinite-based palladium pincer complexes

Aerobic oxidation of organic compounds is receiving attention because molecular oxygen is an abundant, cheap and comparatively safe reagent. Several catalyst systems have been developed so far, but the priority is efficiency and the use of more sustainable reaction media. Here the synthesis of two bis-phosphinite-based palladium(II) complexes has been improved to overcome the lack of reproducibility from previous reports. The improvement relied on solvent modification, strictly inert conditions, monitoring by phosphorus-31 nuclear magnetic resonance, quick filtration and solvent removal steps. We show that both palladacycles are excellent palladium sources for the oxidation of secondary benzyl carbinols in the presence of molecular oxygen at atmospheric pressure. Oxidation of secondary benzyl carbinols carried out in the presence of a very small amount of such palladium complexes, of 0.01 mol%, provided the corresponding ketones in 35–91% yield. High turnover number values, of 3500–9100, substoichiometric amounts of base, of 10 mol%, and the environmentally friendly solvent polyethylene glycol 400 are additional advantages.

Metal-free oxidation of secondary benzylic alcohols using aqueous TBHP

ABSTRACTWe report a simple, yet efficient metal-free oxidation of secondary benzylic alcohols in the presence of t-butyl hydroperoxide (70% TBHP) with high yields of up to 98%. This type of reaction can be carried out using a wide variety of substrates, requires no other organic solvent, and proves to be tolerant toward a variety of different functional groups.

ChemInform Abstract: Sodium Bromide‐Catalyzed Oxidation of Secondary Benzylic Alcohols Using Aqueous Hydrogen Peroxide as Terminal Oxidant.

AbstractThe scalable reaction has a broad substrate scope and tolerates various functional groups including primary hydroxy groups.

Sodium Bromide-Catalyzed Oxidation of Secondary Benzylic Alcohols Using Aqueous Hydrogen Peroxide as Terminal Oxidant

A halide salt, hydroperoxide and AcOH catalyst system was applied to the oxidation of secondary benzylic alcohols. This simple system can be applied to a variety of secondary benzylic alcohols and scaled up for gram-scale preparation. High secondary benzylic alcohol selectivity of the present method is demonstrated in hydroxyketone synthesis. Based on several experimental results, a catalytic cycle for our oxidation is proposed.

Efficient oxidation of secondary alcohols to Ketones by NaOCl catalyzed by Salen-Mn(III)/NBS

An efficient catalytic system salen-Mn(III)/NBS for oxidation of secondary alcohols to ketones by inexpensive and readily available oxidizing agent NaOCl has been developed. The process resulted in good to excellent yields under the action of 2 mol % of salen-Mn(III) and 13 mol % of NBS at room temperature. However, such system was not efficient in oxidation of secondary benzyl alcohols with a strong electronicdonating substituent attached to the benzene ring due to bromination of the alcohols.

Sustainable Flow Oppenauer Oxidation of Secondary Benzylic Alcohols with a Heterogeneous Zirconia Catalyst

A flow chemistry process for the Oppenauer oxidation of benzylic secondary alcohols using partially hydrated zirconium oxide and a simple carbonyl containing oxidant such as acetone, cyclohexanone, and neopentanal is reported. The heterogeneous oxidative system could be applied to a wide range of functionalized alcohol substrates, allowing clean and fast delivery of ketone products within a few minutes between 40 and 100 °C.

Chemoselective Metal-Free Aerobic Alcohol Oxidation in Lignin

An efficient organocatalytic method for chemoselective aerobic oxidation of secondary benzylic alcohols within lignin model compounds has been identified. Extension to selective oxidation in natural lignins has also been demonstrated. The optimal catalyst system consists of 4-acetamido-TEMPO (5 mol %; TEMPO = 2,2,6,6-tetramethylpiperidine-N-oxyl) in combination with HNO3 and HCl (10 mol % each). Preliminary studies highlight the prospect of combining this method with a subsequent oxidation step to achieve C-C bond cleavage.

Application and Mechanistic Studies of a Water‐Oxidation Catalyst in Alcohol Oxidation by Employing Oxygen‐Transfer Reagents

By using a dimeric ruthenium complex in combination with tert-butyl hydrogen peroxide (TBHP) as stoichiometric oxidant, a mild and efficient protocol for the oxidation of secondary benzylic alcohols was obtained, thereby giving the corresponding ketones in high yields within 4 h. However, in the oxidation of aliphatic alcohols, the TBHP protocol suffered from low conversions owing to a competing Ru-catalyzed disproportionation of the oxidant. Gratifyingly, by switching to Oxone (2 KHSO(5)⋅KHSO(4)⋅K(2)SO(4) triple salt) as stoichiometric oxidant, a more efficient and robust system was obtained that allowed for the oxidation of a wide range of aliphatic and benzylic secondary alcohols, giving the corresponding ketones in excellent yields. The mechanism for these reactions is believed to involve a high-valent Ru(V)-oxo species. We provide support for such an intermediate by means of mechanistic studies.

ChemInform Abstract: Oxidation of Secondary Benzylic Alcohols to Ketones and Benzylic Oxygenation of Alkylarenes with Hydrogen Peroxide in Presence of Activated Carbon.

AbstractThe method is successfully applied to various substrate types.

Oxidation of Secondary Benzylic Alcohols to Ketones and Benzylic Oxy­genation of Alkylarenes with Hydrogen Peroxide in the Presence of Activated Carbon

A variety of benzylic alcohols were oxidized to the corresponding carbonyl compounds selectively with 30% hydrogen peroxide (H₂O₂) in the presence of activated carbon. Alkylarenes such as fluorenes, xanthenes, and anthrone were also effectively oxygenated to the corresponding carbonyl compounds with 30% H₂O₂ as oxidant in the presence of activated carbon.

ChemInform Abstract: A Remarkable Effect of Ionic Liquids in Transition‐Metal‐Free Aerobic Oxidation of Benzylic Alcohols.

AbstractThe oxidation of secondary benzylic alcohols is efficiently promoted by ionic liquid as solvent additive.

ChemInform Abstract: Aerobic Oxidation of Secondary Benzylic Alcohols and Direct Oxidative Amidation of Aryl Aldehydes Promoted by Sodium Hydride.

AbstractOxidation of (het)aromatic secondary alcohols (I) and (IV) proceeds smoothly under the action of air/oxygen and NaH to give the corresponding ketones (II) and (V), respectively.

Pd/C Catalyzed Oxidation of Secondary Benzylic Alcohols using Chlorobenzene under an Inert Condition

This research was supported by BasicScience Research Program through the National ResearchFoundation of Korea (NRF) funded by the Ministry ofEducation, Science and Technology (2010-0028217). M. L.appreciated the financial support from the Korean Ministryof Education through the second stage of the BK21 projectfor the Hanyang University graduate program, and alsoacknowledged the Seoul Metropolitan Government forSeoul Science Fellowship.

Aerobic oxidation of secondary benzylic alcohols and direct oxidative amidation of aryl aldehydes promoted by sodium hydride

We reported herein new reactivities and possible mechanistic implications of a simplest oxidant (NaH/air) uncovered on a broad range of useful transformations, including aerobic alcohol oxidations, allylic alcohol isomerizations and oxidations, cyclopropyl alcohol fragmentations, and direct aryl aldehyde oxidative amidations. These readily implementable transition-metal-free processes feature exceptional material accessibility, operational simplicity, and environmental compatibility, and add new dimensions to its synthetic utilities that are fairly robust yet had not previously been fully realized and systematically explored.

Palladium NCN and CNC pincer complexes as exceptionally active catalysts for aerobic oxidation in sustainable media

The oxidation of secondary benzyl alcohols is catalyzed by two palladacycles at atmospheric pressure in PEG-400, a sustainable reaction media. Recycling of the active catalytic species is performed up to the 5th run, and catalyst loadings decreased down to 10−8 mol%, thus achieving unprecedented TON and TOF values. In addition, the same conditions proved to be effective for the aerobic oxidation of benzyl methylene compounds, a scarcely explored process by palladium catalysts.

ChemInform Abstract: Oxidation of Secondary Benzylic Alcohols to Ketones by Activated Carbon—Molecular Oxygen System.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 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.

Oxidation of Secondary Benzylic Alcohols to Ketones by Activated Carbon–Molecular Oxygen System

Abstract A variety of benzylic alcohols were oxidized to the corresponding carbonyl compounds selectively in the presence of activated carbon under molecular oxygen atmosphere. This process does not require any metal oxides, thus this is environmentally friendly and economical.

Oxidation of benzylic alcohols and sulfides over LaCoO3 and TBHP

A simple and efficient methodology has been described for the selective oxidation of secondary benzylic alcohols to the corresponding ketones. In contrast, primary benzylic alcohols afforded dimethyl acetals.