Isomerization of acetylenic acids with sodium salt of 1,2-diaminoethane: a one step synthesis of megatomoic acid

A number of isomeric tetradecynoic acids were isomerized with the sodium salt of 1,2-diaminoethane. Isomers having the triple bond near the carboxyl group rearranged to E,Z-3,5- and E,E-3,5-tetradecadienoic acids (1 and 2), the former compound being the sex pheromone of the black carpet beetle. Isomers having the triple bond closer to the terminus of the chain afforded some 13-tetradecynoic acid along with 1 and 2. Delocalized anions 12 and 13 are thought to contribute to the formation of 1 and 2.