An easy and practical synthesis of all(E)-2,4,6,8,10-dodecapentaenoic
acid (1), all(E)-5,7,9,11,13-pentadecapentaenoic acid (2), all(E)-8,10
,12,14,16-octadecapentaenoic acid (3) and its (8Z)-isomer (4) by appli
cation of the Wittig olefination reaction is described.