Solvent Effect in Reaction of Singlet Oxygen with Conjugated Dienes

Abstract

The 1,4-cycloaddition of singlet oxygen (¹O₂) to conjugated dienes provides a useful tool for simultaneous functionalization of the diene moiety, and its application to organic synthesis has been reported.¹ For the dienes bearing an allylic hydrogen, especially for the dienes not constrained to s-cis conformation, the 1,4-cycloaddition usually competes with the “ene” reaction as well as the 1,2-cycloaddition.² The efficiency of the oxygenation³ and the selectivity of the reaction modes are essential factors in the synthetic application. We have investigated the sensitized photooxygenation of representative acyclic dienes and vinylarenes i n various solvents.