On the mechanism of intramolecular photocycloaddition of substituted o-allylphenols to cyclic ethers

Abstract

Osmometric and NMR techniques were used in order to study the ionic mechanism for the intramolecular photocycloaddition reaction of o-allyl phenols ( 1) to give cyclic ethers ( 2) + ( 3). The role of the intramolecular H-bond between the OH group and the π-electrons of the allylic group was ascertained. based on the results of the photocyclization, osmometric and NMR measurements the substituents can be divided into 3 groups according to their effect on the above intramolecular interaction.