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High Yielding (high + yielding)
Selected AbstractsGold(III) Chloride-Catalyzed Diastereoselective Alkylation Reactions with Chiral Benzylic AcetatesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7-8 2008Philipp Rubenbauer Abstract Gold(III) chloride was shown to be an efficient catalyst for the diastereoselective CC bond formation of various chiral para -methoxybenzylic acetates and different nucleophiles. All electrophilic acetates carried next to the reacting center a stereogenic carbon center bound to a functional group (FG), a methyl substituent and a proton. Selectivities were good (dr>80/20) in favor of the anti -product for FG=COOMe, NO2, CN and in favor of the syn -product for FG=SO2Et, PO(OEt)2. The reactions proceed most likely via a free carbocation, in which a face differentation is facilitated by a preferred conformation. Several arene nucleophiles were shown to be compatible with the catalysis conditions providing the corresponding substitution products in high yields (13 examples, 62,98%). Moreover, other nucleophiles (allyltrimethylsilane, trimethylsilyl cyanide, 2,2-dimethyl-3-(trimethylsilyloxy)butane, p -toluenesulfonamide, and acetylacetone) reacted with a representative chiral electrophile in a high yielding and diastereoselective fashion. [source] Substitution-reduction: an alternative process for the [18F]N -(2-fluoroethylation) of anilinesJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 4 2004Emmanuelle Briard Abstract Substitution of a halo atom (chloro or bromo) in easily prepared N -haloacetyl-anilines with no-carrier added (NCA) cyclotron-produced [18F]fluoride ion (18F, t1/2= 109.8 min; ,+=96.9%), followed by reduction with borane,tetrahydrofuran (BH3,THF), provides an alternative route to NCA [18F]N -(2-fluoroethyl)-anilines. This two-step and one-pot process is rapid (,50 min) and moderately high yielding (,40% decay-corrected radiochemical yield (RCY) overall). In the nucleophilic substitution reaction, 18-crown-6 is preferred to Kryptofix® 222 as complexing agent for the solubilization of the counter-ion (K+), derived from an added metal salt, in acetonitrile. Weakly basic potassium bicarbonate is preferred as the added metal salt. Inclusion of a small amount of water, equating to 4,5 molar equivalents relative to 18-crown-6, base or precursor (held in equimolar ratio), is beneficial in preventing the adsorption of radioactivity onto the wall of the glass reaction vessel and for achieving high RCY in the nucleophilic substitution reaction. BH3,THF is effective for the rapid reduction of the generated [18F]N -fluoroacetyl-aniline to the [18F]N -(2-fluoroethyl)-aniline. Copyright © 2004 John Wiley & Sons, Ltd. [source] Incidence of Error in Oestrus Detection Based on Secondary Oestrus Signs in a 24-h Tie-Stalled Dairy Herd with Low FertilityREPRODUCTION IN DOMESTIC ANIMALS, Issue 4 2009RMSBK Ranasinghe Contents Oestrus detection error and conception rates after AI based only on secondary oestrus signs were evaluated in a high yielding, 24-h tie-stalled dairy herd with low fertility, using milk progesterone profiles. Oestrus detection was based on the secondary oestrus signs such as restlessness, swelling, congestion of vulva and clear mucus discharge. Sixty eight AI conducted after observing the secondary oestrus signs in 44 animals were included in the study. Of the 68 AI, 53 (77.9%) were conducted in the follicular phase, and 13 (19.1%) and 2 (2.9%) were carried out in the luteal phase and during pregnancy, respectively. The overall error in oestrus detection based on milk progesterone profiles was 22.1%. The oestrus detection error did not differ significantly among different secondary oestrus signs. None of the AI conducted in the luteal phase resulted in conception, whereas 20.8% of AI conducted in the follicular phase resulted in conception. No significant difference in the conception rates among the groups of cows with different secondary oestrus signs was shown. The high incidence of oestrus detection error in this study might have been caused by the detection of cows in oestrus based only on secondary oestrus signs due to the confinement of animals. In conclusion, there was a high incidence of heat detection error in the 24-h tie-stalled dairy herd and oestrus detection based only on secondary oestrus signs resulted in low conception rate. [source] Does Plant Variety Protection Contribute to Crop Productivity?THE JOURNAL OF WORLD INTELLECTUAL PROPERTY, Issue 2 2009Lessons for Developing Countries from US Wheat Breeding The application of intellectual property rights (IP) in developing countries is and remains highly controversial, particularly as regards applications to food/agriculture, and pharmaceuticals, which have direct ramifications for large numbers of peoples. One dimension complicating a reasoned dialogue on the public benefits of IP, particularly when many developing countries are implementing the Agreement on Trade-Related Aspects of Intellectual Property Rights (TRIPS) as mandated by membership in the World Trade Organization, is a dearth of information on their actual operation and effects. In this study, we address one particular aspect of the limited documentation on the effects of IP systems, the effect of plant variety protection (PVP) on the genetic productivity potential of varieties. Specifically, we examine wheat varieties in Washington State, United States, which are produced by both public and private sector breeders. Results from the study show that implementation of PVP attracted private investment in open pollinated crops such as wheat in the United States and provided greater numbers of varieties of these crops, which are high yielding from both the public and private sectors. These results may provide some insights for policy makers from developing countries on the effects of IP for plants as their TRIPS commitments are being implemented. [source] Analysis of durum wheat germplasm adapted to different climatic conditionsANNALS OF APPLIED BIOLOGY, Issue 2 2010L. Mondini A study of the extent and patterns of microsatellite diversity in 234 genotypes from Ethiopian durum wheat (Triticum turgidum) landraces was conducted to identify areas of diversity that could be used as a source of new germplasm for developing high yielding and stable varieties. Landraces belonging to nine populations, from three Ethiopian regions [Tigray (T), Gonder (G) and Shewa (S)] with different climates, were analysed by using 28 simple sequence repeat (SSR) markers. The level of polymorphism was high and quite consistent among populations underlining the great diversity existing. The highest level of diversity was found within populations, about 75.9%, while about 5.3% was attributed to differences between regions. The level of expected heterozygosity was on an average, rather high, ranging from 39% to 56%, whereas the observed heterozygosity was, on an average, limited to 14%. An average of about five alleles per locus was detected in each population. Nevertheless, alleles were not equally present in populations as confirmed by the high level of expected heterozygosity. The polymorphism information content (PIC) for the markers assessed showed a wide range of values from 0.14 to 0.92. The likelihood relationships among the nine Ethiopian populations indicated that the material collected in the Gonder region (a wet climate) was genetically more diverse than the materials from Shewa and Tigray (dryer climates). The high number of loci in linkage disequilibrium (LD), up to 23, has demonstrated that the loci were associated irrespective of their physical location. This holds true even if the loci are located on different chromosome arms. Genetic diversity values between populations was very different and was used to produce a dendrogram showing population relationships. [source] | ||||||||||