Catalytic Synthesis of Aldehydes and Ketones under Mild Conditions Using TEMPO/Oxone
Carsten Bolm,* Angelika S. Magnus, and Jens P. Hildebrand
*Institut für Organische Chemie der RWTH Aachen, Landoltweg 1,
52056 Aachen, Germany, Email: carsten.bolm
oc.rwth-aachen.de
C. Bolm, A. S. Magnus, J. P. Hildebrand, Org. Lett., 2000, 2, 1173-1175.
DOI: 10.1021/ol005792g
Abstract
A novel, metal-free oxidation system for the catalytic synthesis of aldehydes and ketones using TEMPO and a quarternary ammonium salt as catalysts and Oxone as oxidant proved especially successful for the synthesis of ketones. The mild conditions tolerate even sensitive silyl protective groups which can otherwise be cleaved in the presence of Oxone.
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Details
The document discusses a novel, metal-free oxidation system using TEMPO/Oxone for the catalytic synthesis of aldehydes and ketones under mild conditions. This method is particularly effective for synthesizing ketones and is compatible with sensitive silyl protective groups. The study explores the influence of various solvents and quaternary ammonium salts on the efficiency of the oxidation process. Dichloromethane (CH2Cl2) was found to be the best solvent for primary alcohols, while toluene was optimal for secondary alcohols. The addition of tetrabutylammonium bromide significantly improved the yields for most substrates. The method avoids over-oxidation to carboxylic acids and is more tolerant of functional groups compared to previous stoichiometric oxidants. The optimized conditions were tested on various primary and secondary alcohols, yielding high conversions to the corresponding aldehydes and ketones. The study also confirmed that TBDMS-ethers remain stable under these oxidation conditions. This TEMPO/Oxone system offers an efficient and mild alternative for alcohol oxidation in organic synthesis.
Silica-Supported TEMPO Catalysts: Synthesis and Application in the Anelli Oxidation of Alcohols
T. Fey, H. Fischer, S. Bachmann, K. Albert, C. Bolm, J. Org. Chem., 2001, 66, 8154-8159.
Key Words
Oxidation, Oxone, Potassium peroxymonosulfat, TEMPO, Aldehydes, Ketones
ID: J54-Y2000-260
