Synthesis and absolute configuration of the male aggregation pheromone of the stink bug Erysarcoris lewisi (Distant), (2Z,6R,1′S,5′S)-2-methyl-6-(4′-methylenebicyclo[3.1.0]hexyl)hept-2-en-1-ol

The structure including the absolute configuration of the male-produced aggregation pheromone of the stink bug Erysarcoris lewisi (Distant) was determined to be (2Z,6R,1'S,5'S)-2-methyl-6-(4'-methylenebicy-clo[3.1.0]hexyl)hept-2-en-1-ol 1 by bioassay and comparison of the H-1 NMR spectrum of the natural pheromone with those of (2Z,6R,1'S,5'S)- and (2Z,6R,1'R,5'R)-isomers. These two diastereomers were synthesized from the corresponding ketones (6R,VS,5'R)- and (6R,VR,5'S)-2, which were prepared by lipase-catalyzed asymmetric acetylation of a mixture of (6R,VS,4'S,5'R)- and (6R,FR,4'R,5'S)-7'-norsesquisabinen-4'-ol 3. The absolute configuration of ketone 2 was assigned by its CD comparison with (1R,5S)-sabina ketone 4. An alternative synthesis of (2Z,6R,1'S,5'S)-1 was achieved without recourse to enzyme by employing Hodgson's diastereoselective intramolecular cyclopropanation as the key step. (C) 2008 Elsevier Ltd. All rights reserved.