Laricinolic acid (8), a new sesquiterpene of the drimane type, has been iso
lated from the wood-rotting fungus Laricifomes officinalis. Its structure w
as elucidated by spectroscopic means and confirmed via a correlation with t
he known drimenine derivative 13. Oxidation of 8 to 1, followed by a mild t
hermal treatment, furnished (-)-officinalic acid (4) in 65% yield. This tra
nsformation establishes the hitherto unknown absolute configuration of the
latter. An independent correlation was achieved by pyrolysis of 4 which fur
nished (-)-dihydrooxoisodrimenine (14) of known absolute configuration.