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| 2. |
- Edlund, Helen
(författare)
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Chemoenzymatic methods for the syntesis of pine sawfly sex peromones
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes the syntheses of pine sawfly sexpheromones via two synthetic routes. The preparation ofenantiomerically pure building blocks for these is alsodescribed.Lipase catalysed methods were developed for either theresolution or desymmetrisation of building blocks. In addition,selective lipase catalysed acylation was investigated as amethod for the preparation of stereoisomerically pure pheromonecomponents.Parameters influencing the kinetic resolution byesterification of 2-methylalkanoic acids catalysed byCandida rugosalipase in organic solvents wereinvestigated. Reproducible enantiomeric ratios (E-values) and reaction rates were obtained by control ofthe water activity both for small scale and preparative scalereactions. Low concentration and long chain length of then-alcohols co-substrate enhanced the selectivity andsimplified the work up procedure. Large-scale esterification ofracemic 2-methyloctanoic acid catalysed byCandida rugosalipase furnished (R)-2-methyloctanoic acid in high yield and afterreduction of the ester product, (S)-2-methyl-1-octanol in a moderate yield, respectively.Both were virtually enantiopure. These building blocksfunctioned as precursor derivatives in the syntheses of theeight possible stereoisomers of 3,7-dimethyl-2-tridecanol,which were used for the identification of the pheromone ofDiprion pini.Either high enantioselectivity or diastereoselectivity wasobtained in lipase catalysed kinetic acylations of a number oferythro- andthreo-3-methyl-2-alcohols, which were needed for theidentification of the pheromones, of several pine sawflyspecies.The possibility to resolve an alternative synthetic buildingblock, useful for the synthesis of pine sawfly pheromones, wasexplored. Thus, (meso/ ± )-2,6-dimethyl-1,7-heptanedioic acid wasesterified withn-butanol catalysed byCandida rugosalipase. Using this method,enantiomerically pure (2R,6R)-2,6-dimethyl-1,7-heptanedioic acid could be obtained,albeit in a low yield.Keywords: pheromone syntheses, pine sawfly,Diprion pini,Gilpinia pallida,Candida rugosa, lipase, kinetic resolution, wateractivity, 2-methylalkanoic acids, 2,6-dimethyl-1,7-heptanedioicacid, 3-methyl-2-alcohols, transesterification,enantioselectivity
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- Hedenström, Erik, et al.
(författare)
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Stereoselective esterification of 2,6-dimethyl-1,7-heptanedioic acid, catalysed by Candida rugosa lipase
- 2003
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Ingår i: Journal of Molecular Catalysis B. - 1381-1177 .- 1873-3158. ; 23:1, s. 53-59
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Tidskriftsartikel (refereegranskat)abstract
- The immobilised Candida rugosa lipase (CRL) displayed S-preference for both stereogenic centres in this sequential esterification of 2,6-dimethyl-1,7-heptanedioic acid (1) (pure meso and meso: (+/-) mixture, 53/47) with n-butanol in cyclohexane at a(w) = 0.8. The reaction was faster when short-chain primary n-alcohols was used and very slow, or even none reactive, when a Ion-chain alcohol was used.
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- Hedenström, Erik, et al.
(författare)
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Synthesis and lipase catalysed stereoselective acylation of some 3-methyl-2-alkanols, identified as sex pheromone precursors in females of pine sawfly species
- 2002
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Ingår i: Journal of The Chemical Society, Perkin Transactions 1. - : Royal Society of Chemistry (RSC). - 1472-7781. ; 2002:15, s. 1810-1817
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Tidskriftsartikel (refereegranskat)abstract
- Several 3-methylalkan-2-ols precursors to sex pheromones of Diprion pini, Gilpinia pallida, Gilpinia frutetorum, Diprion nipponica, Macrodiprion nemoralis and Microdiprion pallipes were synthesised as stereoisomeric mixtures in moderate to good yields. The key reaction sequence in the syntheses was the ring opening of either cis- or racemic trans-epoxybutane using a higher order cyanocuprate as nucleophile followed by a highly efficient lipase catalysed stereoselective acylation of the obtained 3-methylalkan-2-ol. The biologically active species specific stereoisomer was synthesised as a single stereoisomer in high stereoisomeric purity, as one in a mixture of two or as one of four stereoisomers when the appropriate 3-methylalkan-2-ol was stereoselectively acylated using a Pseudomonas sp. lipase as catalyst.
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- Herz, Annette, et al.
(författare)
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First use of pheromones to detect phenology patterns and density relationships of pine sawflies in German forests
- 2000
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Ingår i: Agricultural and Forest Entomology. - : Wiley. - 1461-9555 .- 1461-9563. ; 2:2, s. 123-129
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Tidskriftsartikel (refereegranskat)abstract
- 1 Monitoring studies of pine sawflies with pheromone traps were performed for the first time in Germany. Pheromone traps baited with species-specific pheromone substances were installed in pine forests at different locations in Bavaria, Brandenburg and Lower Saxony during two years. 2 It was possible to track the flight phenology of Diprion pini, Gilpinia pallida and Neodiprion sertifer reliably and to get information about the number of generations of these species in 1997 and 1998. 3 A clear relationship between trap catch and population density could not be detected, but qualitative changes in trap catch caused by different density levels were observed. 4 For D. pini, trap catches were different among endemic populations of different forest types. Furthermore, catches of males reflected the results from the regular cocoon collections by foresters during the previous winter. 5 For N. sertifer, trap catches in endemic populations were well separated from trap catches on sites with higher sawfly densities. However, no significant correlation between trap catch and sawfly density or defoliation level could be found. These results suggest that the efficacy of the pheromone traps probably varied with biological features (sex ratio, density level, immigration) of the particular population.
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- Johansson, Björn, et al.
(författare)
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Release Rates for Pine Sawfly Pheromones from Two Types of Dispensers and Phenology of Neodiprion sertifer
- 2001
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Ingår i: Journal of Chemical Ecology. - 0098-0331 .- 1573-1561. ; 27:4, s. 733-745
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Tidskriftsartikel (refereegranskat)abstract
- Comparisons of release rates, duration in the field, and catch efficiency of polyethylene and cotton roll dispensers for the sex pheromones of sawflies (Hymenoptera: Diprionidae) were conducted. The release rates of the Neodiprion sertifer (Geoffr.) and Diprion pini (L.) sex pheromones, the acetates of pentadecanol and (2S,3S,7S)-3,7-dimethyl (2S,3R,7R)-3,7-dimethyl-2-tridecanol from polyethylene dispensers were measured at different temperatures in the laboratory. The release rates for the substances depended on both the temperature and initial load in the vials. The catch from cotton rolls baited with 100 μg of the acetate or propionate of 3,7-dimethyl-2-pentadecanol was compared to the catch from regularly renewed cotton rolls baited with 10 μg of the same acetate. The catch was higher for the 100-μg cotton rolls for, at most, 45 days, and there was no significant difference in catch between the acetate and the propionate. The catch in traps baited with polyethylene or cotton roll dispensers loaded with the acetate of 3,7-dimethyl-2-pentadecanol was compared and showed that cotton roll traps mirrored the decreasing release of the substance rather than the actual flight activity. The length of the flight period of N. sertifer in Sweden, the Czech Republic, Italy, and Greece did not exceed 100 days in any of the countries. By adjusting the initial pheromone load of the polyethylene vials to the expected temperatures, it should be possible to get a constant and sufficiently high release rate during the entire flight period.
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