Web Release Date: July 20,
Concise Preparation of the (3E,5Z)-Alkadienyl System. New Approach to the Synthesis of Principal Insect Sex Pheromone Constituents
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Department of Chemistry, Laboratory of Organic Chemistry, University of Athens, Panepistimiopolis Zographou, 157 71 Athens, Greece, and VIORYL S.A., Research Department, 28th Km Athens-Lamia Nat. Road, 19014 Afidnes, Greece
Received for review April 13, 2004. Revised manuscript received May 23, 2004. Accepted June 5, 2004.
Abstract:
A new rapid and low-cost preparation of the (3E,5Z)-3,5-alkadienyl system, encountered in several insect pheromone constituents, was developed. Knoevenagel condensation of (E)-2-alkenals with ethyl hydrogen malonate in dimethyl sulfoxide, in the presence of a catalytic amount of piperidinium acetate, led to a mixture of geometrical isomers of ethyl 3,5-alkadienoates and ethyl 2,4-alkadienoates, from which the (3E,5Z)-3,5-alkadienoate was conveniently separated, by the use of urea inclusion complex formation. The importance of this procedure has been illustrated by the preparation of the (3E,5Z)-3,5-tetradecadienoic acid (megatomoic acid) 1, the (3E,5Z)-3,5-dodecadienyl acetate 2, and the (3E,5Z)-3,5-tetradecadienyl acetate 3. These compounds are the main components of insect sex pheromones and constitute synthetic targets of considerable interest for the semiochemical community.
Keywords: Knoevenagel condensation; pheromone synthesis; semiochemicals; megatomoic acid; Attagenus megatoma; Bonagota cranaodes; Recurvaria leucatella
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