“…Further assignments of the basic skeleton of 9-desacetoxymelcanthin F were deduced from extensive double irradiation experiments and 13C-nmr data, the results being summarized in Tables 1 and 2. The great similarity of the nmr spectral data of lactone 1 with cis,cisgermacranolides from Melampodium species (5,6) suggested a similar skeleton for compound 1. A three-proton singlet at 3.79, typical of a carbomethoxy methyl, together with the downfield absorption of H-l at 6.81 indicated a m-l(10)-double bond (6).…”