Tetrahedron Letters,Vol.25,No.l6,Pp 1643-1646,1984 oo40-4039/84 $3.00 + .OO Printed in Great Britain 81984 Pergamon Press Ltd. SYNTHESIS OF THE THREE ISOMEKIC COMPONENTS OF SAN JOSE SCALE PHEROMONE Margot Alderdice, Claude Spino, and Larry Weiler* Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada V6T lY6 Abstract: The three isomeric components of the San Jose scale pheromone have been synthe- sized stereospecificallyfrom a common intermediate S-keto ester. which fruit Three (1). The San Jose scale, Quadraspidiotuspernicious, is a serious world-wide insect pest attacks fruit, shade, and ornamental trees. It is particularlyharmful to deciduous trees, and for this reason it is a serious economic pest in North Ameritan orchards. active components, l-3, have been isolated from the pheromone mixture of female scales NN Al1 three components were found to be almost equally attractive to male scales (1). In this paper, we report a stereospecificsynthesis of each of the isomers of the pheromone from a common precursor. *OCOE+ I ‘-ocoE+ 2 3 Recently, we have developed a stereoselectivemethod to convert a S-keto ester into the alkene 4, as shown in equation 1 (2). We now report methods to convert this same S-keto ester into the alkene 2 and the l,l-disubstituted alkene 6. 0 [,] R&COOMe 1. Na;, zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA CIPO(OEt)2 ) 2.R,CUli OCOD R ,k,,COOMe 5 6 1643