Ferruginene A (1) was isolated as a brownish-yellow, amorphous solid, [R] D þ107.7 (c 0.052, MeOH). Analysis of its 1H
and 13C NMR spectroscopic data revealed signals for 22 carbons and 28 protons (Table 1). The molecular formula of C22H30O4 was determined by HRESIMS, which showed a deprotonated molecular ion at m/z 357.2079 [M H] (calcd for C22H29O4 357.2071). The carbon backbone of 1 was determined using COSY, HSQC, andHMBC NMR spectroscopy (Table 1). Thus,