Conformations of ten-membered-ring sesquiterpenes. Crystal and molecular structures of agerol diepoxide and ageratriol

Abstract

The crystal and molecular structures of agerol diepoxide (3) and ageratriol (2), which have been determined by direct methods and refined by least-squares to R 0.060 and 0.069 respectively, confirm the previously suggested biogenetic scheme from agerol (1). Theoretical calculations by a molecular mechanics method (GEMO program) show that the conformers observed in the crystals have the lowest strain-energy. N.m.r. measurements indicate that agerol diepoxide adopts this conformation also in solution.