A Concise Asymmetric Access to the Active Pheromone Components of the Monarch butterfly and the Azuki Bean Weevil

A concise and efficient asymmetric synthesis of (S,E)-3,7-dimethyl-2-octene-1,8-diol and (S,E)-3,7-dimethyl-2-octene-1,8-dioic acid, two biologically important insect pheromone components have been developed. The strategy combines a Grignard-type carbon–carbon bond formation step with a zirconocene-catalyzed carboalumination reaction, enabling efficient construction of the unsaturated carbon framework and the remote stereogenic center. The optimized route affords (S,E)-3,7-dimethyl-2-octene-1,8-diol in seven steps and 38% overall yield, with an enantiomeric purity of 98% ee. This approach provides a practical platform for the preparation of structurally related insect pheromone components in high enantiomeric purity.