Photochemistry of 2,4-Cyclooctadienone I. In Benzene and Toluene

Publisher Website
Google Scholar
Abstract
Irradiation of 2,4-cyclooctadienone (1) in benzene or toluene is shown to give in >80% yield two head-to-head dimers. The ring fusions are shown to occur at the α,β-positions of the dienone with trans-cis and trans-anti-trans stereochemistry. Both dimers may be epimerized to the same product with cis-anti-cis ring fusions. Evidence is presented to show that the singlet state is responsible for the cis-trans isomerization of 1 to the highly reactive intermediate trans, cis-2,4-cyclooctadienone. This intermediate can dimerize in a thermal 2 + 2 cycloaddition or can be generated at −78° and then trapped by 1,3-dienes in a Diels–Alder reaction. A mechanism for the dimerization reaction is discussed.

This publication has 0 references indexed in Scilit: