Expedient synthesis of quadrilure antipodes, the pheromone of square-necked grain beetle

Article abstract of DOI:10.1016/0957-4166(95)00031-J

Both the enantiomers of the title pheromone, (E)-3-methyl-7-acetoxynon-3-ene (I) have been synthesized in high enantiomeric excess via a stereoselective route. Thus, easily accessible, 3-methylpent-1-en-3-ol (2) was converted via a Claisen orthoester rearrangement to the ester (3) with exclusive (E)-geometry. Its derivatization to the aldehyde (5) followed by reaction with ethylmagnesium bromide gave the racemic pheromone alcohol (6) in 27.7% overall yield. Its enantioselective lipase catalyzed trans-esterification directly afforded (R)-I, while its antipode was obtained from the resolved alcohol by chemical acetylation.