Studies on the synthesis of sesquiterpene lactones, 12. Synthesis of (+)-colartin, (+)-arbusculin A, and their C-4 epimers and their biological activities.

Colartin [9] and arbusculin A [11] have been synthesized from alpha-santonin [1] in 14.5% (11 steps) and 9.3% (13 steps) overall yields, respectively. Arbusculin A [11] and compounds 20, 21, and 22, which were derived from intermediate 2, showed significant cell growth inhibitory activity against murine lymphocytic leukemia (P-388) in vitro. Plant growth regulating activity of 11 and its synthetic intermediates 4, 5, 8, and 9 was also studied.