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The oxyfunctionalization of 4‐methylcoumarins using dimethyldioxirane
Author(s) -
Ćavar Sanja,
Kovač Franci
Publication year - 2009
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.20412
Subject(s) - dimethyldioxirane , chemistry , regioselectivity , hydroxylation , double bond , coumarin , photochemistry , structural isomer , reaction rate constant , kinetic energy , molecule , organic chemistry , stereochemistry , kinetics , catalysis , physics , quantum mechanics , enzyme
The kinetic study of the efficient regioselective oxidation of the CC 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