New Dolabellane Derivatives from the Brown Alga Dictyota pardalis

Reinvestigation of the brown alga Dictyota pardalis f. pseudohamata C RIBB 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 (1 R *,3 S *,7 S *,11 R *,4 Z )‐dolabella‐4,8(17), 12(18)‐triene‐3,7‐diol ( 1 ), (1 R *,3 S *,4 S *,7 S *,8 S *,11 R *,14 R *,12 E )‐3,4:7,8‐diepoxydolabe11‐12‐ene‐14, 18‐diol ( 2 ), and (1 R *,3 S *,4 S *,7 S *,8 S *,11 R *,14 R *)‐3,4:7,8‐diepoxy‐l,4,8,12,12‐pentamethylbicyclo[9. 3. 0]tetra‐decan‐14‐ol( 3 ).