The objectives will be to develop improved chemical syntheses for biologically significant natural products and their structural analogs. These syntheses are destined to rely upon new procedures for effecting episulfonium ion initiated carboannulations which we have recently discovered. Specific molecules targeted for synthesis include the anti-cancer agent taxodione and the morphinan analgesics. The cytotoxin taxodione has exhibited significant activity in vivo against Walker intramuscular carcinsarcoma 256 in rats and in vitro against cells derived from human carcinoma of the nasopharnyx (KB). The analgesic morphine and its analogs have a rich history of clinical use for the relief of severe pain resulting from physical trauma and chronic illnesses. In addition to the above objectives, the utilization of sulfenium ion promoted cyclizations involving vinylcyclopropane and higher order polyene initiators will be synthetically evaluated.