| 101. |
- Smitt, Olof, et al.
(författare)
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First Total Synthesis of (-)-1(10),5-Germacradien-4-ol
- 2002
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Ingår i: Synlett. - : Georg Thieme Verlag KG. - 0936-5214 .- 1437-2096. ; 2002:8, s. 1273-1276
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a total synthesis of (-)-1(10),5-germacradien-4-ol, a constituent of the needles of Scots pine and of the defence secretion from the larvae of the pine sawfly. The synthesis uses a strategy based on an intramolecular alkylation to form an unsaturated monocyclic 10-membered ring.
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| 102. |
- Smitt, Olof, et al.
(författare)
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Syntheses of a prenylbisabolane diterpene, a natural insecticide from Croton linearis, and of the bisabolane sesquiterpenes (-)-delobanone and (-)-epi-delobanone
- 2002
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Ingår i: Tetrahedron. - 0040-4020. ; 58:38, s. 7691-7700
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Tidskriftsartikel (refereegranskat)abstract
- An enantioselective first total synthesis of a constituent of Croton linearis, the (-)-7-hydroxy-3,10-prenylbisaboladien-2-one 1, is described as well as the syntheses of the 7-hydroxy-3,10-bisaboladien-2-ones (-)-epi-delobanone (14a) and (-)-delobanone (14b). The model compounds, 7-hydroxy-11-nor-methyl-3-bisabolen-2-one (8a), and 11,15-nor-dimethyl-7-hydroxy-3-bisabolen-2-one (8b), were successfully prepared by opening of the protected carvone epoxide derivative 6 with the appropriate organocuprates. An alternative approach was used for compounds 1 and 14. Thus, these were obtained from homogeranyllithium or homoprenyl Grignard reagent, which reacted successfully with a masked nor-carvone, ketone 11, prepared in four steps from (R)-carvone.
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| 103. |
- Svedberg, U. R. A., et al.
(författare)
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Emission of hexanal and carbon monoxide from storage of wood pellets, a potential occupational and domestic health hazard
- 2004
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Ingår i: Annals of Occupational Hygiene. - : Oxford University Press (OUP). - 0003-4878 .- 1475-3162. ; 48:4, s. 339-349
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The objective of the present study was to investigate and describe the emissions of volatile compounds, particularly hexanal and carbon monoxide, from large- and small-scale storage of wood pellets.Methods: Air sampling was performed with Fourier transform infrared spectroscopy and adsorbent sampling in pellet warehouses, domestic storage rooms, lumber kiln dryers and experimental set-ups. Literature studies were included to describe the formation of hexanal and carbon monoxide and the toxicology of hexanal.Results: A geometric mean aldehyde level of 111 +/- 32 mg/m(3) was found in one warehouse, with a peak reading of 156 mg/m(3). A maximum aldehyde reading of 457 mg/m(3) was recorded at the surface of a pellet pile. Hexanal (70-80% w/w) and pentanal (10-15% w/w) dominated, but acetone (821 +/- 24 mg/m(3)), methanol (18 7 mg/m(3)) and carbon monoxide (56 +/- 4 mg/m(3)) were also found. The emissions in a domestic storage room varied with the ambient temperature and peaked after 2 months storage in the midst of the warm season. Aldehyde levels of 98 +/- 4 mg/m(3) and carbon monoxide levels of 123 +/- 10 mg/m(3) were recorded inside such storage rooms. Elevated levels of hexanal (0.084 mg/m(3)) were recorded inside domestic housing and 6 mg/m(3) in a room adjacent to a poorly sealed storage area. Experimental laboratory studies confirmed the findings of the field studies. A field study of the emissions from industrial lumber drying also showed the formation of aldehydes and carbon monoxide.Conclusions: High levels of hexanal and carbon monoxide were strongly associated with storage of wood pellets and may constitute an occupational and domestic health hazard. The results from lumber drying show that the emissions of hexanal and carbon monoxide are not limited to wood pellets but are caused by general degradation processes of wood, facilitated by drying at elevated temperature. Emission of carbon monoxide from wood materials at low temperatures (<100degreesC) has not previously been reported in the literature. We postulate that carbon monoxide is formed due to autoxidative degradation of fats and fatty acids. A toxicological literature survey showed that the available scientific information on hexanal is insufficient to determine the potential risks to health. However, the data presented in this paper seem sufficient to undertake preventive measures to reduce exposure to hexanal.
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| 104. |
- Verheggen, F, et al.
(författare)
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Electrophysiological and Behavioral Activity of Secondary Metabolites in the Confused Flour Beetle, Tribolium confusum
- 2007
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Ingår i: Journal of Chemical Ecology. - : Springer Science and Business Media LLC. - 0098-0331 .- 1573-1561. ; 33:3, s. 525-539
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Tidskriftsartikel (refereegranskat)abstract
- Several previous studies have addressed pheromone communication in various flour beetles (Coleoptera: Tenebrionidae), including the confused flour beetle, Tribolium confusum (du Val). Different stereoisomers of 4,8-dimethyldecanal (DMD) were reported as the only components of an aggregation pheromone, but the behavioral activity of DMD is low. In the present study, additional previously reported secondary metabolites (benzoquinones and hydrocarbons) were tested for electrophysiological activity (EAG) with both sexes of T. confusum. Two benzoquinones and three monoenic hydrocarbons elicited significant EAG activity from both male and female antennae. There was an elevated male EAG response (vs. the females) to two out of the three hydrocarbons and for both quinones. The EAG-active compounds were subsequently investigated for behavioral activity in a walking bioassay. Benzoquinones are considered toxic and have been assigned a function as alarm substances in flour beetles, but we found that methyl-1, 4-benzoquinone in intermediate concentrations was attractive to both male and female beetles and could therefore act as an aggregation pheromone component. Males were also attracted to ethyl-1,4-benzoquinone. The corresponding hydroquinones, presumed precursors of the benzoquinones, did not elicit any electrophysiological response and were not tested for behavioral activity. The unsaturated hydrocarbons (1-tetradecene, 1-pentadecene, and 1-hexadecene) elicited significant EAG responses from both male and female antennae and were also attractive in the behavioral assay. Our results show that several beetle-produced compounds, in addition to 4,8-dimethyldecanal, may be part of a complex pheromone system in flour beetles and play a role in mediating aggregation in T. confusum.
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| 105. |
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| 106. |
- Wassgren, Ann Britt, et al.
(författare)
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Pheromone related compounds in pupal and adult female pine sawflies, Neodiprion sertifer, of different age and in different parts of the body
- 1992
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Ingår i: Journal of Insect Physiology. - 0022-1910. ; 38:11, s. 885-893
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Tidskriftsartikel (refereegranskat)abstract
- The pine sawfly pheromone precursor 3,7-dimethyl-2-pentadecanol (diprionol) was quantified by gas chromatography in different body parts of virgin female Neodiprion sertifer. About one-third of the total amount (approx. 10 ng per female) was found in each of head + thorax, abdominal segments 1-3, and the remaining abdomen. Diprionol was also found in the respective parts of pupae, but in lower amounts. This suggests that at least the final steps of the pheromone biosynthesis take place in many parts of the body, possibly in the cuticle. The diprionol content remained relatively constant over the whole lifetime of virgin females. By using coupled gas chromatography-electroantennogram detection three active compounds in the acetylated female extract were observed. These corresponded to the pheromone, (2S,3S,7S)-diprionyl acetate, and its homologues with the chain shortened by one and two carbons respectively, as determined by gas chromatography-mass spectrometry. In addition, the homologue having a chain elongated by one carbon was found. The homologues occurred in amounts of 2-5% of the diprionyl acetate. When synthetic homologues were tested in the field, alone or in combination with diprionyl acetate, they were not behaviourally active to male sawflies, despite their electroantennogram activity. A threo-isomer of diprionol, most likely (2S,3R,7R), was present in the females in amounts less than 0.5% of the (2S,3S,7S)-content. The acetate of this threo-isomer is known as both synergist and inhibitor to the (2S,3S,7S)-isomer. trans-Perillenal was found in the abdominal segments 1-3 of both males and females and its possible biosynthetic relationship to diprionol is discussed.
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| 107. |
- Wassgren, A.-B., et al.
(författare)
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Sex Pheromone of the Pine Sawfly Macrodiprion nemoralis (Hymenoptera : Diprionidae) : Identification of (2S,3R,7R,9S)-3,7,9-Trimethyl-2-tridecanol as the Precursor for the Active Pheromone Acetate
- 2000
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Ingår i: Die Naturwissenschaften. - : Springer Science and Business Media LLC. - 0028-1042 .- 1432-1904. ; 87:1, s. 24-29
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Tidskriftsartikel (refereegranskat)abstract
- The main component of the sex pheromone precursor in females of Macrodiprion nemoralis was identified as a threo-3,7,9-trimethyl-2-tridecanol isomer, approximately 800 pg per female, by gas chromatography-mass spectrometry. Comparison of mass spectrometric ion chromatograms showed that the natural compound in the female extract has the same retention time and mass spectrum as one of the two synthetic threo peaks. The acetate of the synthetic 16-isomer mixture caught a large number of males in the field, confirming the structure of the active pheromone. Comparison of gas chromatograms of the natural female extract with the eight synthetic threo stereoisomers showed that the pheromone is the (2S,3R,7R,9S)-stereoisomer of 3,7,9-trimethyl-2-tridecyl acetate.
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| 108. |
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| 109. |
- Östrand, Fredrik, et al.
(författare)
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Stereoisomeric composition of the sex pheromone of the pine sawfly Microdiprion pallipes (Hym., Diprionidae)
- 2003
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Ingår i: Chemoecology. - : Springer Science and Business Media LLC. - 0937-7409 .- 1423-0445. ; 13:3, s. 155-162
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Tidskriftsartikel (refereegranskat)abstract
- The basic chemical structure of the sex pheromone of the pine sawfly Microdiprion pallipes (Fallen) has earlier been identified as the propionate ester of (2S,3S,7 R/S,11 R/S)/(2R,3R,7 R/S,11 R/S)-3,7,11-trimethyl-2-tridecanol. We now report the results from further investigations on the male response to individual stereoisomers and to blends of stereoisomers, both in electroantennographic (EAG) recordings and in field trapping experiments. We also present our attempts to determine the stereochemistry of the compounds present in females of M. pallipes. By comparing gas chromatograms and mass spectra obtained from natural extracts with those from synthetic compounds it was found that the females contain one or more of the four (2S,3S,7 R/S,11 R/S)-3,7,11-trimethyl-2-tridecanol isomers (SS++-1). The active pheromone component is the corresponding propionate ester 2. In EAG experiments, males responded most strongly to five propionate ester samples, namely two four-isomer blends: SS++-2 and SR++-2, and three individual stereoisomers: SSSR-, SRRR- and SRSR-2. In a series of field trapping experiments it was found that males were attracted to the SR++-2 four-isomer blend and to the individual isomer SSSR-2. Based on the EAG-recordings and field responses of males and the stereoisomers found in the females, we suggest that the propionate ester of (2S,3S,7S,11R)-3,7,11-trimethyl-2-tridecanol (SSSR-2) is used as a main component of the sex pheromone in M. pallipes. Apparently the males react to other stereoisomers in addition to that or those produced by the females.
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