“…The above evidence, coupled with a NMR comparison with compound 1 6,28) , and analysis of 1 H-1 H COSY, HMQC, HMBC, and NOESY ( ) spectra, confirmed that 32 was a diterpene acid possessing an isocopalane-type skeleton, i.e., 7a-acetoxy-3-oxoisocopala-1,13-dien-15-oic acid. This diterpene is corresponded to a ring-D cleavage product of azadirone-and azadiradione-type limonoids.…”