Transtaganolides A-D: novel metabolites from Thapsia transtagana.

Four novel and unusual C-19 compounds from Thapsia transtagana, named transtaganolides A-D, have been isolated. Their structures were established by physical methods, including X-ray analysis of transtaganolides A and B. This is the first time that a 7-methoxy-4,5-dihydro-3H-oxepin-2-one ring has been found in a natural product. [structure: see text]