Photocycloaddition Reaction of 8-Methoxypsoralen and 5,7-Dimethoxycoumarin with Maleimide

摘要

C4-Photocycloaddition of 8-methoxypsoralen (8-MOP) and 5,7-dimethoxycoumarin (DMC) to maleimide was studied in order to elucidate the mechanism of the photobiological activities of these molecules. The photoreaction was carried out in chloroform solution and frozen aqueous solution state. The major product was isolated and characterized by spectroscopic methods. The photoadduct between 8-MOP and maleimide was shown to be an 1:1 C4-cycloadduct through the photocycloaddition of 4`,5`-furyl double bond of 8-MOP to maleimide. The stereochemistry of cyclobutane ring of this photoadduct is consistent with the anti configuration. The photoadduct between DMC and maleimide was shown to be an 1:1 C4-cycloadduct through the photocycloaddition of 3,4-pyrone double bond of DMC to maleimide.