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1-(2-Oxiranyl)-1,4-alkanediones were prepared from the ethylene acetals of ethyl 4-oxoalkanoates via the oxidation of the intermediate 1,2-dialkylcyclopropanols having a protected carbonyl group in an aliphatic chain. Intramolecular acetalization of these epoxy dicarbonyl compounds gave alkylated 6,8-dioxabicyclo[3.2.1]octan-2-ones in good yields. The latter were found suitable to be precursors for (±)-endo-brevicomin and its 2-hydroxy derivative, as well as (±)-endo-isobrevicomin and (±)-frontalin. 相似文献
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Kenji Mori Shigefumi Kuwahara Mitsuhiko Fujiwhara 《Journal of Chemical Sciences》1988,100(2-3):113-117
A mixture of the four stereoisomers of 2.6-dimethyloctyl formate was synthesized, and found to be a potent mimic of (4R,8R)-4,8-dimethyldecanal, the aggregation pheromone of the flour beetles,Tribolium castaneum andTribolium confusum.
For Part CVI, see Mori K and Puapoomchareon P 1988Liebigs Ann. Chem. 175 相似文献
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J.S. Yadav Sandip Sengupta Nagendra Nath Yadav D. Narasimha Chary Ahmad Alkhazim Al Ghamdi 《Tetrahedron letters》2012,53(44):5952-5954
(−)-Lardolure and (2R,4R,6R,8R)-2,4,6,8-tetramethylundecanoic acid have been synthesized via lipase catalyzed desymmetrization strategy to create two methyl chiral centers. Other key steps involved in the synthesis are Wittig reaction, Evan’s asymmetric alkylation, Grignard reaction, Pd-catalyzed isomerization of primary allylic alcohol to corresponding saturated aldehyde, and PhNO/proline catalyzed MacMillan α-hydroxylation. 相似文献
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Christian R. Noe Max Knollmüller Karin Dungler Peter Gärtner 《Monatshefte für Chemie / Chemical Monthly》1991,122(3):185-194
Summary Starting from substituted methoxythiophenes1 ketones and spiroketals can be synthesized in one step by desulfurization with partial hydrogenation. The bark beetle pheromone chalcogran2 a and the wasp anti aggression pheromone2 b were prepared by this method.
Prof. Dr. F. Sauter zum 60. Geburtstag gewidmet 相似文献
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Attraction and repulsion are responses to chemical stimuli which can be received and processed even by unicellular organisms without a morphologically defined nervous system. Chemical substances trigger off a chain of events which starts with a membrane-bound signal receptor and, after a sequence of regulatory and modulatory steps, ends in the modulation of a motor effector organ. Binding of the signal substances to the receptor produces conformational changes in which the receptor subunits are mutually dependent on one another, and also leads to chemical modification of the subunits and affects their molecular activity. These interactions, together with the characteristic type of movement, result in a physiological pattern of behavior which enables the flagellated sex cells (gametes) of marine brown algae to finally locate their partners. The simple but highly specific brown algae gamete systems have been investigated structurally and their biological activity analyzed. The signal substances are mainly highly unsaturated aliphatic or cyclic hydrocarbons with unsaturated side chains (general formula e. g. C11H14, C11H16, C11H18). These systems also serve as a simplifying model which helps in the understanding of complex ganglionic pathways in higher living organisms where the sense organs convey information from the surroundings to the central nervous system through nerve pathways. The information is then processed and answered, via efferent pathways, as movement. 相似文献
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An efficient strategy for the synthesis of 2,6-dialkyl-2,3-dihydro-4H-pyran-4-ones has been developed, the key steps of which are oxidative cleavage of the three-membered rings of 1-(2-oxoalkyl)-cyclopropanols and acid-promoted cyclization of the resulting β-hydroxyketones. 相似文献
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Ingolf Lamprecht 《Thermochimica Acta》1997,300(1-2):213-224
Direct calorimetric experiments on the social insects: honeybees, bumblebees and hornets are described as function of castes, age, number of animals in a group, temperature, sound generation, hibernation and influence of pheromones. Two honeybee subspecies, the European bee Apis mellifera carnica and the Egyptian bee Apis mellifera lamarckii, were compared calorimetrically in their energy metabolism which differed considerably in favour of the more alert Egyptian form.
Moreover, thermoelectric cooling boxes for camping were applied as simple heat conduction calorimeters and as artificial nesting facilities for bumblebees and hornets. Their colonies could be monitored calorimetrically and thermometrically throughout the season. In spring, initial nests with only a few workers and one queen were collected in the field and transferred to these boxes where they continued their normal development up to full size of several hundred individuals. By this means, energy turnover of insect colonies could be evaluated under varying conditions. 相似文献
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Techniques are available for the gas chromatography of very small samples of insect pheromones and defensive secretions by which the diluting and contaminating effects of solvents are avoided. Samples obtained in many ways can be sealed in fine glass capillaries, heated and crushed on-column to give quantitative high-resolution chromatograms. Reactions can be carried out in a micro-reactor and the reaction products obtained in a very small volume (5 μl) for chromatography without evaporation. 相似文献