NEW SYNTHETIC METHODS : A GENERAL AND EFFICIENT APPROACH TO RING - FUSED CYCLOHEPTADIENESl

The widespread occurrence of functionalized cycloheptane and ring-fused cycloheptane ring systems in numerous classes of natural products has made them the synthetic targets of many investigators. 2 Despite recent advances in hydroasulene syntheses, 3 there are almost no general and direct approaches to ring-fused cycloheptadienes which would also allow for incorporation of numerous labile functionalities. The compelling need for new and efficient methodology in this area of synthesis is reinforced by the isolation of many highly oxygenated sesquiterpene lactones which show significant antitumor activity. 4