Photochemistry of nonconjugated bichromophoric systems III. Synthesis and photoreaction of poly(ethylene glycol) biscoumarinyloxyacetates

A series of poly(ethylene glycol) biscoumarinyloxyacetates have been synthesized and their intramolecular photochemical cyclodimerizations have been studied. It was found that only syn-HT configuration products were obtained when these bisesters were directly irradiated in chloroform, and the yields of the products decreased with the increase of the chain length. This photocyclization reaction is a convenient and effective method to synthesize macrocyclic compounds.