Studies on the rearrangement of 8α,9α-epoxy-12,12-ethylenedioxypodocarpan-16-ol acetate by boron trifluoride–ether. Formation of a novel product containing a C-seco, B-aromatic system

Abstract

The rearrangement of 8α,9α-epoxy-12,12-ethylenedioxypodocarpan-16-ol acetate (3b) has been studied. Upon treatment with boron trifluoride–ether in a polar solvent (nitromethane), the epoxide (3b) yielded, besides compounds (8) and (7d), (9a) as the major product. In a non-polar solvent (benzene), however, compounds (18), (5c), and (5d) were obtained under the same conditions.