Synthesis of (2S,7S)-dibutyroxynonane, the sex pheromone of the orange wheat blossom midge, Sitodiplosis mosellana (Géhin) (Diptera: Cecidomyiidae), by diastereoselective silicon-tethered ring-closing metathesis

The sex pheromone of Sitodiplosis mosellana, (2S,7S)-dibutyroxynonane, has been synthesised using a mixed di-t-butylsilaketal prepared from (S)-5-hexen-2-ol and prochiral 1,4-pentadiene-3-ol. Ring-closing metathesis occurs diastereoselectively and after the removal of the silyl group and the reduction of the double bonds, generates (2S,7S)-nonanediol with a diastereoisomeric excess of 94% as measured by gas chromatographic analysis of the diacetylated product.

The sex pheromone of the orange wheat blossom midge is synthesised by RCM from a sterically hindered silaketal with a de of 94%.