Studies on the Syntheses of Biologically Active Sesquiterpene Lactones.

Many biologically interesting eudesmanolides have been synthesized from commercilly available a-santonin and their biological activities have been studies. The eudesmanolides functionalized at C-1 were then demonstrated to be efficient common intermediates for the syntheses of elemanolides and guaianolides. Thus the fragmentation reaction of 36 with Al(iPrO)3 gave a new route to the synthesis of elemanolides and germacranolides. The solvolytic rearrangement of 36, 49, 63, and 99 gave efficient intermediates for the syntheses of naturally occurring guaianolides