IBX/n-Bu₄NBr/CH₂Cl₂-H₂O: a new mild system for selective oxidation of secondary alcohols

Chutima Kuhakarn*, Krisada Kittigowittana, Manat Pohmakotr and Vichai Reutrakul

*Department of Chemistry, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand, Email: scckkmahidol.ac.th

C. Kuhakarn, K. Kittigowittana, M. Pohmakotr, V. Reutrakul, Tetrahedron, 2005, 61, 8995-9000.

DOI: 10.1016/j.tet.2005.07.051

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Abstract

A chemoselective oxidation of secondary alcohols with IBX/n-Bu₄NBr in CH₂Cl₂-H₂O gave ketones in good yields and allowed the oxidation of secondary hydroxyl group even in the presence of primary hydroxyl groups.

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Details

The document discusses a new method for the selective oxidation of secondary alcohols to ketones using a system comprising 2-iodoxybenzoic acid (IBX) and tetrabutylammonium bromide (n-Bu₄NBr) in a dichloromethane-water (CH₂Cl₂-H2O) solvent mixture. This method is notable for its high chemoselectivity, allowing the oxidation of secondary hydroxyl groups in the presence of primary hydroxyl groups within the same molecule, yielding ketones in moderate to good yields at room temperature. The study highlights the optimization of reaction conditions, including the choice of phase transfer catalysts and solvent ratios, with n-Bu₄NBr proving to be the most effective catalyst. The method was tested on various substrates, demonstrating its efficiency and selectivity. The research aims to provide a mild, efficient, and environmentally friendly alternative to existing oxidation methods, avoiding the use of moisture-sensitive and toxic reagents. The findings are expected to be of significant interest to the chemistry community, particularly in the synthesis of complex molecules where selective oxidation is crucial. The document also includes detailed experimental procedures and characterization data for the products obtained.

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Key Words

Selective oxidation, Ketones, IBX oxidation

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ID: J72-Y2005-3060