Synthesis of exo-Bicyclooct-5-ene-dicarboxylic Anhydrides by Thermal Isomerization of trans-Diacids

Article abstract of DOI:10.1021/jo00260a003

Bicyclo<2.2.2>oct-5-ene-trans-1,2-dicarboxylic acid and substituted analogues afford mixtures of the corresponding exo- and endo-anhydrides upon heating at 250-300 deg C.This isomerization provides a practical pathway to substituted and deuterium-labeled exo-anhydrides which are otherwise difficult to obtain.A mechanistic study shows that retro-diene fragmentation is not involved in the isomerization.