Photochemistry of nonconjugated bichromophoric systems. I. Synthesis and photoreaction of polymethylene bis - coumarinyloxyacetates

A series of polymethylene bis - coumarinyloxyacetates have been synthesized and their intramolecular photochemical cyclomerization have been studied. It was found that only syn - HT configuration products were obtained when these bis - esters were directly irradiated in chloroform, and the yields of the products decreased with the increase of chain length. The crystal structure of product 3b was determined by X - ray diffraction analysis.