Two New Highly Oxidized Humulane Sesquiterpenes from the Basidiomycete Lactarius mitissimus

Two new highly oxidized humulane sesquiterpenes, mitissimols F (1) and G (2), were isolated from the fruiting bodies of Lactarius mitissimus. Their structures were elucidated by using extensive spectroscopic techniques including 1D- and 2D-NMR experiments. The absolute configuration of mitissimol F (1) was determined by 1H-NMR resolution of its diastereoisomeric α-methoxy-α-(trifluoromethyl)benzeneacetates (MTPA). It was shown to be (1S,3E,6S,8R,9R,10S,11R)-8,9 : 10,11-diepoxy-1,6-dihydroxyhumul-3-en-5-one (=(1S,2R,4R,6S,8E,11S,12R)-6,11-dihydroxy-1,6,10,10-tetramethyl-3,13-dioxatricyclo[10.1.0.02,4]tridec-8-en-7-one).