Stereoselective Synthesis of Methyl Branched Eicosa-5(Z), 9(Z)-dienoic Acids, Components of the Sponge,Erylus formosus

A stereoselective synthesis of two marine fatty acids viz. 19-methyleicosa-5(Z), 9(Z)-dienoic acid (I) and 18-methyleicosa-5(Z), 9(Z)-dienoic acid (II) has been developed. The synthetic strategy was based on C‒C bond formation via (Z)-selective Wittig olefination of the required synthons which in turn were prepared from readily available materials.