Cyclopentadienone Dimers

Abstract

The exposure of solid, red 2,5-dicarboethoxy-3,4- di(4-methylphenyl)cyclopentadienone to visible light results in the formation of a colorless “dimer”. The cyclopentadienone is synthesized from 4,4’-dimethylbenzil and diethyl 1,3- acetonedicarboxylate. The structure of the “dimer” includes a central eight membered ring with two bridging carbonyls that shows interesting characteristics in the solid and solution state. It appears to be photochemically unstable in solution and undergoes transesterification on recrystallization from 1- propanol. Further research is in progress on this ring system to understand what manipulations it can undergo and how these manipulations affect its reactivity.