Adduct Formation in the Photoreactions of Benzylic Ethers with Quinones

Article abstract of DOI:10.1021/jo00090a022

Irradiation of 1,4-benzoquinone (BQ) in the presence of a series of benzylic ethers results in an adduct composed of one molecule of quinone and one molecule of the ether.In addition to the formation of this adduct, cleavage of the benzylic ether to the corresponding aldehyde and alcohol was observed.The amount of adduct formed was dramatically increased when the reaction was conducted in benzene.This is in contrast to the results of irradiation with 2,3-dichloro-5,6-dicyanoquinone (DDQ) where no adduct was isolable and only bond cleavage was observed.The major product of 2,5-dichloroquinone (DCQ) irradiation was bond cleavage of the benzylic ethers, but a small amount of adduct was observed as a reaction product.The formation of adducts in these quinone irradiations can be explained by the slower rate of adduct hydrolysis by lower potential quinones.