Reactivity of 4-vinylphenol radical cations in solution: implications for the biosynthesis of lignans.
Nanosecond laser flash photolysis studies of the radical cation of 4-hydroxy-3-methoxystyrene show that the radical cation reacts with neutral 4-hydroxy-3-methoxystyrene and non-phenolic styrenes with rate constants that range from 1 x 10(8) to 5 x 10(8) M(-1) s(-1). Similar 4-vinylphenol radical cations such as the radical cations of isoeugenol and coniferyl alcohol display reduced reactivity, presumably due to the presence of beta-alkyl substituents. Overall, the results show that the reactivity of 4-vinylphenol radical cations with neutral styrenes parallels the reactivity of non-phenolic styrene radical cations, which are known to undergo efficient radical cation mediated dimerization reactions to give lignan-like compounds. The possibility that the biosynthesis of some lignans may follow a radical cation mediated mechanism is discussed.
Rodríguez-Evora
Yan
Y
Department of Chemistry, Dalhousie University, Halifax, Nova Scotia B3H 4J3, Canada.
Schepp
Norman P
NP
D002412:Cations / Q000737:chemistry; D005609:Free Radicals / Q000737:chemistry; D017705:Lignans / Q000096:biosynthesis* / Q000737:chemistry*; D015394:Molecular Structure; D019800:Phenol / Q000737:chemistry; D010636:Phenols / Q000737:chemistry*; D012996:Solutions; D013057:Spectrum Analysis; D013343:Styrenes / Q000737:chemistry
D002412:Cations; D005609:Free Radicals; D017705:Lignans; D010636:Phenols; D012996:Solutions; D013343:Styrenes; D019800:Phenol; C030626:4-vinylphenol