Concise preparation of the (3E,5Z)-alkadienyl system. New approach to the synthesis of principal insect sex pheromone constituents.
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.
Ragoussis
Valentine
V
Department of Chemistry, Laboratory of Organic Chemistry, University of Athens, Panepistimiopolis Zographou, 157 71 Athens, Greece. ragousi@chem.uoa.gr
Panopoulou
Maria
M
Ragoussis
Nikitas
N
D000466:Alkadienes / Q000737:chemistry*; D000818:Animals; D008401:Gas Chromatography-Mass Spectrometry; D006860:Hydrogen Bonding; D007313:Insecta / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D012724:Sex Attractants / Q000138:chemical synthesis*
D000466:Alkadienes; D012724:Sex Attractants