Abstract The four isomeric 5, 10-pentadecadienals 1, 2, 3 and 4 were prepared by stereo- selective routes from acetylenic precursors. Two of them, 2 and 4, were also made by Wittig reaction from 2-hydroxytetrahydropyran (29). 2-Hydroxytetrahydropyran (29) yields (Z)-5- alkenols efficiently by Wittig reaction, and (Z)-4-hexenol was similarly made from 2- hydroxytetrahydrofuran (66).
