New Dolabellane Derivatives from the Brown Alga Dictyota pardalis

Reinvestigation of the brown alga Dictyota pardalis f. pseudohamata CRIBB led to the crystallization of 1 and to the isolation of the two new dolabellane derivatives 2 and 3. X‐Ray analysis of 1 and 2, together with detailed 1D‐and 2D‐NMR studies on 2 and 3, allowed their structures to be elucidated as (1R*,3S*,7S*,11R*,4Z)‐dolabella‐4,8(17), 12(18)‐triene‐3,7‐diol (1), (1R*,3S*,4S*,7S*,8S*,11R*,14R*,12E)‐3,4:7,8‐diepoxydolabe11‐12‐ene‐14, 18‐diol (2), and (1R*,3S*,4S*,7S*,8S*,11R*,14R*)‐3,4:7,8‐diepoxy‐l,4,8,12,12‐pentamethylbicyclo[9. 3. 0]tetra‐decan‐14‐ol(3).