The oxyfunctionalization of 4-methylcoumarins using dimethyldioxirane

✍ Scribed by Sanja Ćavar; Franci Kovač

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 203 KB
• Volume: 41
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.20412

✦ Synopsis

Abstract

The kinetic study of the efficient regioselective oxidation of the CC double bond of 4‐methylcoumarins with isolated dimethyldioxirane was investigated using UV–vis spectroscopy methods. In the excess of dimethyldioxirane, the pyrone ring of a coumarin skeleton is selectively epoxidated and hydroxylated in neutral media, in high yields. Kinetic analyses demonstrate two independent reaction pathways, epoxidation and hydroxylation, respectively, which was also confirmed using kinetic isotope effect methods. Both reaction products were isolated, and their structures were determined by NMR and mass spectra. The position of methyl groups attached at the aromatic part of coumarin molecule shows significant influence on kinetic rate constants and activation parameters. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 414–420, 2009