The isolation of three highly oxygenated guaianolides, desacetyl-1 alp
ha,4 alpha-dihydroxybishopsolicepolide [1], its 4 beta-hydroxy epimer
2 (a new compound), and 1 beta,2 beta:3 beta,4 beta-diepoxy-8 alpha,10
alpha-dihydroxyguai-11(13)-en-12,6 alpha-olide [3], from the aerial p
arts of Achillea crithmifolia is reported. Because lactone 3 was shown
to be identical with rupin A, the initially proposed 1 alpha,2 alpha:
3 alpha,4 alpha-diepoxy stereochemistry of rupin A should be revised.