The Synthesis and Transformation of Nitrones for Organic Synthesis

Nitrones are important compounds and are highly useful in many aspects. The first part describes the methods for synthesis of nitrones, which are useful and environmentally friendly. Catalytic oxidations, condensations, and other useful reactions are described. The nitrones thus obtained are key intermediates for the synthesis of biologically important nitrogen compounds. The second part describes the fundamental transformations of nitrones, which will provide the strategies and means for the construction of nitrogen compounds. The reactions with nucleophiles or radicals, C—H functionalization, and various addition reactions are described. The last reactions are particularly important for highly selective carbon—carbon bond formations. 1,3-Dipolar cycloaddition reactions are excluded because the size of the review is limited and excellent reviews have been published in Chem. Rev

Development of biomimetic catalytic oxidation methods and non-salt methods using transition metal-based acid and base ambiphilic catalysts

This review focuses on the development of ruthenium and flavin catalysts for environmentally benign oxidation reactions based on mimicking the functions of cytochrome P-450 and flavoenzymes, and low valent transition-metal catalysts that replace conventional acids and bases. Several new concepts and new types of catalytic reactions based on these concepts are described

Copper complexes for catalytic, aerobic oxidation of hydrocarbons

Abstract: Catalytic oxidation of hydrocarbons can be performed efficiently upon treatment with tert-butylhydroperoxide or peracetic acid in the presence of a low-valent ruthenium catalyst. Furthermore, aerobic oxidation of hydrocarbons can be performed in the presence of acetaldehyde using ruthenium, iron, and copper catalysts. Copper derived from copper chloride/crown ether or copper chloride/crown ether/alkaline metal salts have proved to be efficient catalysts. Further study revealed that specific copper complexes formed from copper salts and acetonitrile are convenient and highly useful catalysts for the aerobic oxidation of unactivated hydrocarbons. Selective oxidation of alkanes is an important topic in view of the economical and ecological use of natural raw materials. However, catalytic oxidation of unactivated hydrocarbons remains as a challenging topic (eq. 1). Direct oxidation of hydrocarbons is one of the important functions of cytochrome P-450. During the course of simulation of the enzymatic functions of cytochrome P-450 with transition-metal complexes, we found that catalytic oxidation of various substrates can be performed highly efficiently The copper complexes derived from copper chloride and crown ethers were found to be extremely efficient catalyst

Oxidation of Primary Amines to Oximes with Molecular Oxygen using 1,1-Diphenyl-2-picrylhydrazyl and WO₃/Al₂O₃ as Catalysts

The oxidative transformation of primary amines to their corresponding oximes proceeds with high efficiency under molecular oxygen diluted with molecular nitrogen (O₂/N₂ = 7/93 v/v, 5 MPa) in the presence of the catalysts 1,1-diphenyl-2-picrylhydrazyl (DPPH) and tungusten oxide/alumina (WO₃/Al₂O₃). The method is environmentally benign, because the reaction requires only molecular oxygen as the terminal oxidant and gives water as a side product. Various alicyclic amines and aliphatic amines can be converted to their corresponding oximes in excellent yields. It is noteworthy that the oxidative transformation of primary amines proceeds chemoselectively in the presence of other functional groups. The key step of the present oxidation is a fast electron transfer from the primary amine to DPPH followed by proton transfer to give the α-aminoalkyl radical intermediate, which undergoes reaction with molecular oxygen and hydrogen abstraction to give α-aminoalkyl hydroperoxide. Subsequent reaction of the peroxide with WO₃/Al₂O₃ gives oximes. The aerobic oxidation of secondary amines gives the corresponding nitrones. Aerobic oxidative transformation of cyclohexylamines to cyclohexanone oximes is important as a method for industrial production of ε-caprolactam, a raw material for Nylon 6