Abstract
Four geometrical isomers of 5, 7-, 6, 8-, 7, 9- and 8, 10-dodecadien-1-ols were systematically synthesized by two routes. One involved the Wittig reaction between (E)-2-alkenal and a phosphorane with an appropriate carbon chain, and yielded a mixture of (E, Z)- and (E, E)-isomers in a ratio of ca. 3:2. The other route comprised of the Wittig reaction of a 2-alkynal and the stereoselective reduction of the triple bond to a (Z)-double bond via hydroboration with dicyclohexylborane to give a mixture of (Z, Z)- and (Z, E)-isomers in a ratio of 6:1-10:1. Both the mixtures were separately chromatographed on a silica gel column impregnated with silver nitrate to give four geometrically pure isomers. With 9, 11-diene they were analysed by GC on a capillary column, HPLC, silver nitrate impregnated TLC, and 13C NMR.
