Stereoselective transformation of cyclodecene-1,4-dione systems, derived from steroids, tot he corresponding spiro-γ-lactones

摘要

The thermal and acid-catalyzed intramolecular rearrangement of the (Z)- and (E)-cy- clodecene-1, 4-dione compounds derived from steroids, 2a, b and 3a, b, respectively, proceeds stereoselectively to give the corresponding configurationally different spiro- γ-lactoen derivatives, the (5R, 9R)-isomers 4a, b(from the (Z)-cyclodecenediones 2a, b) and the (5R, 9S)-isomers 5a, b (from the (E)-cyclodecenediones 3a, b). A possible mecha- nistic pathway of the observed intramolecular process leading to the spiro-γ-lactone structures is discussed.