Pyridones, well-known for their ability to photodimerize, have been found to undergo [4+ 4] photocycloaddition with furan and naphthalene but not with benzene. In some cases these reactions can be highly regio-and stereospecific. Intramolecular reaction with furan produces both cis and trans [4+ 4] products. The cycloaddition with naphthalene can occur both inter-and intramolecularly. The intermolecular reaction yields primarily the cis isomer, ...
