18-Iodooctadeca-(8Z,11Z)-dienoic acid (7) was synthesized in five steps starting from methyl 10-bromodec-7-ynoate (2) in an overall yield of 53%. The synthetic procedure involves Cu(I)-catalyzed cross-coupling of propargylic bromide 2 with 7-octyn-1-ol (3), followed by hydrogenation of the coupling product 4 to Z,Z-diene 5 on Lindlar's catalyst and subsequent substitution of the OH– group of 5 with iodine. Coupling of the resulting iodide 7 with low-order organic cuprates [t-Bu2CuLi or (PhCH2)2CuMgCl] leads to 19,19-dimethyleicosa-(8Z,11Z)-dienoic acid (1a) and 19-phenylnonadeca-(8Z,11Z)-dienoic acid (1b), respectively.