Diterpenoids. XI. A Synthesis of Hydrofluorene Derivatives (trans-A/B-Ring Fusion (β C₅-H))

Abstract

c-Homofluorene (VI) having undeniable trans-A/B-ring fusion has been previously synthesized from 1-abietic acid (I). In order to have a standard trans-A/B-ring hydrofluorene (XIII), basic skeleton of gibberellin, c-homofluorene (VI) was chosen as starting material and its seven membered alicyclic C-ring was contracted to benzene ring.