Search results for "Alkene"
showing 10 items of 98 documents
A Stereocontrolled Protocol to Highly Functionalized Fluorinated Scaffolds through a Fluoride Opening of Oxiranes
2016
A novel selective and substrate-dependent synthetic protocol has been developed towards the synthesis of various fluorine-containing, highly functionalized cycloalkane derivatives. The method involves the stereoselective epoxidation of some unsaturated cyclic beta-amino acid derivatives as model compounds, followed by a regioselective fluoride opening of oxiranes under various conditions with Deoxofluor and XtalFluor-E reagents, thereby offering an insight into this new epoxide opening methodology with fluoride.
Stereoselective Total Synthesis and Absolute Configuration of the Natural Decanolides (−)-Microcarpalide and (+)-Lethaloxin. Identity of (+)-Lethalox…
2005
[reaction: see text] Convergent, stereoselective syntheses of the pharmacologically active, naturally occurring lactones (-)-microcarpalide and (+)-lethaloxin have been achieved from the commercially available, chiral reagents (R)-glycidol, (S,S)-tartaric acid, and d-ribose as the starting materials. These syntheses have further served to establish the hitherto unknown absolute configuration of (+)-lethaloxin and to show its identity with (+)-pinolidoxin.
Di- and Tetrairon(III) μ-Oxido Complexes of an N3S-Donor Ligand: Catalyst Precursors for Alkene Oxidations
2019
The new di- and tetranuclear Fe(III) μ-oxido complexes [Fe 4 (μ-O) 4 (PTEBIA) 4 ](CF 3 SO 3 ) 4 (CH 3 CN) 2 ] (1a), [Fe 2 (μ-O)Cl 2 (PTEBIA) 2 ](CF 3 SO 3 ) 2 (1b), and [Fe 2 (μ-O)(HCOO) 2 (PTEBIA) 2 ](ClO 4 ) 2 (MeOH) (2) were prepared from the sulfur-containing ligand (2-((2,4-dimethylphenyl)thio)-N,N-bis ((1-methyl-benzimidazol-2-yl)methyl)ethanamine (PTEBIA). The tetrairon complex 1a features four μ-oxido bridges, while in dinuclear 1b, the sulfur moiety of the ligand occupies one of the six coordination sites of each Fe(III) ion with a long Fe-S distance of 2.814(6) A. In 2, two Fe(III) centers are bridged by one oxido and two formate units, the latter likely formed by methanol oxidati…
End Capping Ring-Opening Olefin Metathesis Polymerization Polymers with Vinyl Lactones
2008
The selective placement of a functional group at the chain end of a ring-opening metathesis polymer using ruthenium carbene initiators has been a significant limitation. Here we demonstrate a highly effective and facile end-capping technique for ROMP with living ruthenium carbene chain ends using single-turnover olefin metathesis substrates. Vinylene carbonate and 3H-furanone are introduced as functionalization and termination agents for the ruthenium-initiated ring-opening metathesis polymerization. This leads directly to the formation of functional polymer end groups without further chemical transformation steps. Aldehyde and carboxylic acid end groups can be introduced by this new method…
Genetic control of pheromones in Drosophila simulans. I. Ngbo, a locus on the second chromosome
1991
0016-6731 (Print) Journal Article; 7-Tricosene and 7-pentacosene are predominant hydrocarbons on the cuticle of both sexes in Drosophila simulans. The pheromonal role of 7-tricosene has been clearly established for conspecific males, while a synergistic effect for 7-pentacosene has been postulated. Interstrain variation for the production of both compounds is very marked, but similar for both sexes. The genetic basis of this polymorphism was investigated. A major role was found for the second chromosome, which controls the 7-tricosene:7-pentacosene ratio. The main locus involved in controlling this variation, Ngbo, was mapped to position 65.3 on the second chromosome. The production of 7-pe…
Co-adaptation of pheromone production and behavioural responses in Drosophila melanogaster males
1999
0016-6723 (Print) Journal Article Research Support, Non-U.S. Gov't; In Drosophila melanogaster, male courtship behaviour is genetically controlled and is influenced by sex pheromones. 7-tricosene (7-T) induces a dose-dependent inhibition of male-male courtship, whereas 7,11-dienes stimulate male courtship of females. There is a geographical quantitative variation in the production of two predominant male hydrocarbons, 7-T and 7-pentacosene (7-P). We have previously found that 7-P, the main hydrocarbon from males of West African strains, stimulates males that mainly produce 7-T. Using both 'natural' and genetically engineered strains, we find that genetic factors coding for low levels of 7-P…
The pheromonal role of cuticular hydrocarbons in Drosophila melanogaster
1997
0265-9247 (Print) Journal Article Research Support, Non-U.S. Gov't Review; Pheromones play a crucial role in mate stimulation and discrimination. In the fruit fly Drosophila, the most abundant cuticular hydrocarbons act as sex pheromones during courtship behavior. There are several active molecules and they compose a sex- and species-specific pheromonal bouquet. Different species from the Drosophila melanogaster subgroup have adopted alternative systems of chemical mate recognition. Recent exploration of these interspecific variations, and of intraspecific variations, has led to the characterization of genes and to the mapping of structures that process the production and perception of chem…
Genetic control of male cuticular hydrocarbons in Drosophila melanogaster
1996
0016-6723 (Print) Comparative Study Journal Article; 7-tricosene (7-T) and 7-pentacosene (7-P) are the two main hydrocarbons on the cuticle of male Drosophila melanogaster. These two substances might play a pheromonal role during courtship behaviour. We investigated the genetic basis of the quantitative polymorphism observed in the production of 7-T and 7-P. Strains of different geographic origin, with males producing either predominantly 7-T or predominantly 7-P, were hybridized with strains carrying genetic markers. We found that chromosome II changes the balance between 7-T and 7-P while chromosome III regulates the overall quantity of both 7-monoenes. We have also characterized and roug…
The role of cuticular pheromones in courtship conditioning of Drosophila males
2005
1072-0502 (Print) Comparative Study Journal Article Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S.; Courtship conditioning is an associative learning paradigm in Drosophila melanogaster, wherein male courtship behavior is modified by experience with unreceptive, previously mated females. While the training experience with mated females involves multiple sensory and behavioral interactions, we hypothesized that female cuticular hydrocarbons function as a specific chemosensory conditioned stimulus in this learning paradigm. The effects of training with mated females were determined in courtship tests with either wild-type virgin females as courtship targets, or with…
A Drosophila male pheromone affects female sexual receptivity.
2006
Sex pheromones are chemical signals frequently required for mate choice, but their reciprocal role on mate preference has rarely been shown in both sexes. InDrosophila melanogasterflies, the predominant cuticular hydrocarbons (CHs) are sexually dimorphic: only females produce 7,11-dienes, whereas 7-tricosene (7-T) is the principal male CH. Males generally prefer females with 7,11-dienes, but the role of 7-T on female behaviour remains unclear. With perfumed males, control females mated faster and more often with males carrying increased levels of 7-T showing that this CH acts as a chemical stimulant forD. melanogasterfemales. Control females—but not antenna-less females—could detect small v…