Abstract
We have shown that the synthesis of di- and triquinane type new antineoplastic substances can be effectively achieved by the subsequent chemical decoration of the basic carbon skeletons of di- and triquinane sesquiterpenes derived easily from the skeletal rearrangement of tricycloundecanes. Our unique synthetic methodology for such biologically active substances is characterized by the following sequences; 1) facile preparation of tricycloundecanes, trimethylenebicyclo [4.2.0] undecan-2-ones, 2) elegant acid- catalyzed rearrangement of tricycloundecanes to build up basic carbon skeletons of natural di-and triquinane sesquiterpenes, 3) α-methylene ketonization for one of cyclopentane rings in basic carbon skeletons. Thus, a variety of new antineoplastic di-and triquinanes were efficiently synthesized and the bioassay indicated that the polycarbocyclic skeletons, surrounding the α-methylene carbonyl functionality, were very significant in exerting the activity. In addition, the synthesis of α-alkylidene dispiro-γ-lactones via skeletal rearrangement of [4.4.2] propella-δ-lactone followed by alkylidenation is described.
