Epoxide across positions C-12 to C-13 |
Two prominent doublets (H-13a and H-13b) in the 1H NMR spectrum (e.g. δ 3.10 and 2.78; J = 4 Hz). |
Double bond across positions C-9 to C-10 |
Prominent broad doublet (with possible allylic coupling at higher field) in 1H NMR spectrum for H-10 (e.g. δ 5.45). |
Vinyl methyl group at position C-16 |
Prominent singlet (with possible allylic coupling at higher field) in 1H NMR spectrum (e.g. δ 1.73). |
Two α,β-unsaturated lactone moieties at positions C-6' to C-11' [e.g. compounds similar to verrucarin A (1)]. |
Prominent UV spectrum with a single maximum (λ ~ 260 nm). |
Additional α,β-unsaturated lactone moieties at positions C-1' to C-3' [e.g. compounds similar to roridin E (2)]. |
Prominent UV spectrum with two maxima (λ ~ 260 and 230 nm). |