The rearrangement of some epoxy podocarpanoic acids

Abstract

Rearrangement of the epoxides derived from the podocarpenoic acids (3b), (3d) and (5b) with boron trifluoride etherate gave compounds with the rosane skeleton, lacking substituents at C 13. The rearrangement involves the shift of a methyl group with concomitant lactonization. The unsaturated acids (3b) and (5b) undergo similar rearrangements when they are treated with boron trifluoride etherate or sulphuric acid.