A facile and efficient synthetic pathway of (3Z,6Z,9Z)-3,6,9-nonadecatriene and homologs: pheromone and attractant components of Lepidoptera

The straight-chain 3,6,9-homoconjugated trienes are common sex pheromone and attractant components for many lepidopterous insect pests. A facile and efficient chemical synthetic pathway of (3Z,6Z,9Z)-3,6,9-nonadecatriene and homologs from commercially available a-linolenic acid [(9Z,12Z,15Z)-9,12,15-octadecatrienoic acid] is reported. The metal catalyzed cross-coupling reactions between (9Z,12Z,15Z)-9,12,15-octadecatrienyl triflate and the appropriate Grignard reagents proceed very rapidly under notably mild conditions using Li2CuCl4 as catalyst in diethyl ether; resulting (3Z,6Z,9Z)-3,6,9-trienes with retention of geometrical configuration were in >92% isolated yield.