Improved Methodology for Photocyclization Reactions

Article abstract of DOI:10.1021/jo00012a005

To photocyclize stilbenes, a stoichiometric amount of iodine plus propylene oxide in the absence of air is superior to a catalytic amount of iodine in the air.The propylene oxide prevents HI from photoreducing double bonds.The absence of air prevents photooxidative side reactions, shown in one case to be caused by a photogenerated oxidant, possibly hydrogen peroxide.