Synthesis, analysis, and field activity of sordidin, a male-produced aggregation pheromone of the banana weevil, Cosmopolites sordidus
1997
Jayaraman, S. | Ndiege, I.O. | Oehlschalger, A.C. | Gonzalez, L.M. | Alpizar, D. | Falles, M. | Budenberg, W.J. | Ahuya, P.
An efficient synthesis of the diastereoisomers of sordidin (1), a male-produced aggregation pheromone of Cosmopolites sordidus, has been developed from commercially available 4-methylpent-4-en-2-ol (2). Preparation of exo-beta-sordidin (1a) and endo-beta-sordidin (1b) is via the anti epoxide, 4d, which is derived via iodocarbonation of 2. The endo-alpha-sordidin (1c) and exo-alpha-sordidin (1d) are prepared from the corresponding syn epoxide, which is available via stereo-controlled epoxidation of the triisopropylsilyloxy derivative, 3b. Silyloxy derivatives of the epoxides, 4, efficiently alkylate the anions of N-cyclohexyldiethylketimine (6a) and 3-pentanone N,n-dimethylhydrazone (6b). Acidic work-up of these alkylation reactions promotes cyclization to give 1. Gram quantities of 1a-1d, 1a + 1b and 1c + 1d have been prepared by this route. In field tests in a banana plantation in Costa Rica, compounds 1a-1d significantly increased capture rates of standard pseudostem traps. Comparable numbers of adults were attracted to pseudostem traps baited with the major naturally occurring isomers of sordidin 1c + 1d or 1a-1d. Although addition of the minor naturally occurring isomers of sordidin (1a and 1b) to pseudostem traps increased capture rates above controls, these compounds did not increase attraction of pseudostem traps to the same extent as 1a-1d. In comparison tests with conventional pseudostem traps, significantly more adults were trapped in water-containing pitfall traps baited with 1a-1d.
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