Visible Light-Mediated Selective Aerobic Oxidation of Alcohols Catalyzed by Disulfide in Batch and Flow

Selective aerobic oxidation of alcohols in batch and flow can be realized under light irradiation, utilizing disulfide as the photocatalyst, and a variety of primary and secondary alcohols were converted to the corresponding aldehydes or ketones in up to 99% yield and high selectivity. The reaction efficiency could be increased even further by combining a continuous-flow strategy. Detailed mechanistic studies have also been achieved to determine the role of oxygen and disulfides in this oxidation.

Catalytic Asymmetric Axially Chiral Allenyl C-P Bond Formation

Chiral organophosphorous compounds are very important in catalysis, organic syntheses, and medicinal chemistry. However, catalytic enantioselective protocols for the axially chiral allenyl phosphorus compounds have never been reported. Herein, a palladium-catalyzed enantioselective carbon-phosphorus bond formation reaction affording axially chiral allenyl phosphonates has been developed. The reaction enjoys high yields and ees accommodating a wide range of functional groups. Mechanistic studies have unveiled an overwhelming kinetic resolution process.

A Highly Efficient Bismuth Nitrate/Keto-ABNO Catalyst System for Aerobic Oxidation of Alcohols to Carbonyl Compounds under Mild Conditions

An efficient and practical catalytic system for the oxidation of alcohols to aldehydes/ketones using catalytic amounts of Bi(NO₃)₃ and Keto-ABNO (9-azabicyclo [3.3.1]nonan-3-one N-oxyl) with air as the environmentally benign oxidant was developed. Various primary and secondary alcohols were smoothly oxidized to the corresponding products under mild conditions, and satisfactory yields were achieved. Moreover, this methodology avoids the use of a ligand and base. The gram-scale reaction was demonstrated for the oxidation of 1-phenyl ethanol, and the product of acetophenone was obtained at an isolated yield of about 94%.

Iron(III) Nitrate/TEMPO-Catalyzed Aerobic Alcohol Oxidation: Distinguishing between Serial versus Integrated Redox Cooperativity

Aerobic alcohol oxidations catalyzed by transition metal salts and aminoxyls are prominent examples of cooperative catalysis. Cu/aminoxyl catalysts have been studied previously and feature "integrated cooperativity", in which Cu^II and the aminoxyl participate together to mediate alcohol oxidation. Here we investigate a complementary Fe/aminoxyl catalyst system and provide evidence for "serial cooperativity", involving a redox cascade wherein the alcohol is oxidized by an in situ-generated oxoammonium species, which is directly detected in the catalytic reaction mixture by cyclic step chronoamperometry. The mechanistic difference between the Cu- and Fe-based catalysts arises from the use iron(III) nitrate, which initiates a NO_x-based redox cycle for oxidation of aminoxyl/hydroxylamine to oxoammonium. The different mechanisms for the Cu- and Fe-based catalyst systems are manifested in different alcohol oxidation chemoselectivity and functional group compatibility.

Nitriles as radical acceptors in radical cascade reactions

The application of the cyano group as a radical acceptor in the cascade reactions for the construction of various important heterocycles and carbocycles was summarized.

Direct electrooxidation of alkynes to benzoin bis-ethers

Electrosynthesis of benzoin bis-ethers from alkynes and alcohols under metal-free and external oxidant free conditions.

Magnetic core–shell Fe3O4@Cu2O and Fe3O4@Cu2O–Cu materials as catalysts for aerobic oxidation of benzylic alcohols assisted by TEMPO and N-methylimidazole

Robust core–shell magnetic materials catalyse quantitatively the aerobic oxidation of a wide range of benzylic alcohols into corresponding aldehydes at room temperature showing excellent tolerance towards the substituents on the phenyl ring.