Structural elucidation of trichotetronines: polyketides possessing a bicyclo[2.2.2]octane skeleton with a tetronic acid moiety isolated from Trichoderma sp.

The isolation and structural elucidation of two novel fungal metabolites, trichotetronine and its dihydro congener, from Trichoderma sp. are described. The structures, including the relative and absolute stereochemistry, have been established using a variety of data including extensive NMR analyses and CD spectral studies. The compounds possess a bicyclo[2.2.2]octene system in conjunction with a tetronic acid moiety and two conjugated ketonic side chains. Along with them, trichodimerol, a known compound possessing an axis of symmetry, has been isolated. Both trichodimerol and the newly isolated trichotetronines appear to be derived from the condensation of two hexaketides having two extra methyl groups.