Search results for "Asymmetric"
showing 10 items of 241 documents
The Economics of Extortion: Theory and Evidence on the Sicilian Mafia
2019
This paper studies extortion of firms operating in legal sectors by a profit-maximizing criminal organization. We develop a simple principal-agent model under asymmetric information to find the Mafia-optimal extortion as a function of firms' observable characteristics, namely size and sector. We test the predictions of the model on a unique dataset on extortion in Sicily, the Italian region where the most powerful criminal organization, the Mafia, operates. In line with our theoretical model, our empirical findings show that extortion is strongly concave in firm's size and highly regressive. The percentage of profits appropriated by Mafia ranges from 40% for small firms to 2% for large firm…
Supported Organocatalysts as a Powerful Tool in Asymmetric Synthesis
2010
Supported Organocatalysts: a Powerful Tool in Organic Synthesis
2012
Advantages in supporting chiral organocatalysts
2010
An overview on the advances in supporting organocatalysts for their use and recycle in the asymmetric synthesis is presented, focusing on the main approaches for the immobilization and highlighting those examples in which supported and unsupported version of the catalyst behave similarly and high level of recyclability have been obtained.
Organocatalytic Enantioselective Alkylation of Pyrazol-3-ones with Isatin-Derived Ketimines: Stereocontrolled Construction of Vicinal Tetrasubstitute…
2016
A quinine-derived thiourea catalysed the enantioselective addition of 4-substituted pyrazolones to isatin-derived ketimines, providing a variety of aminooxindole-pyrazolone adducts containing congested vicinal tetrasubstituted stereocentres with excellent outcomes (up to 98% yield, >20:1 dr and 98% ee).
Organic carbonates as alternative solvents for asymmetric hydrogenation
2009
Organic carbonates like propylene carbonate (PC) or butylene carbonate (BC) belong to the class of aprotic, highly dipolar solvents (AHD). Interestingly, their potential as solvents for asymmetric catalysis has been overlooked for a long time. The aim of this work is to evaluate organic carbonates and other organic solvents like THF, CH2Cl2, and acetonitrile as well as members of the AHD-family (DMF, DMSO, etc.) as media for homogeneous asymmetric hydrogenation. For this reason cationic Rh-complexes based on chiral phosphine ligands were tested in the hydrogenation of typical benchmark substrates. In several trials, significant advantages of organic carbonates were found. In contrast to DMS…
IS MEANING WITHOUT ACTUALLY EXISTING REFERENCE NATURALIZABLE?
1995
Sex- and age-related variation in survival and cost of first reproduction in Greater Flamingos
2001
International audience; We analyzed survival of breeding Greater Flamingos, Phoenicopterus ruber roseus, using the capture histories of 2000 breeding birds ringed as chicks and resighted at their natal colony in the Camargue, southern France. As found in previous analyses, recapture probability varied according to year, sex, and age of the bird, and annual survival was strongly affected by winter severity. However, by using a much larger data set than in earlier analyses, we detected previously nonsignificant effects. Indeed, for the first time, sex and age of the bird were found to influence annual survival probability. We tested the hypothesis that the observed sex-related difference in s…
Synthesis of ortho-fonctionnalized arylphosphines and their applications
2020
This thesis reports with the synthesis of ortho-functionnalized phosphines bearing phosphonium and 1,2,3-triazole moieties.The synthesis of phosphines-phosphoniums, using as key-step Phospha-Fries rearrangement and Appel reaction is described. Eight new phosphines- phosphoniums, bearing aryl, alkyl or ferrocenyl fragments on the phosphonium part, have been prepared with overall yields reaching 48%. These phosphines- phosphoniums have been used in the preparation of gold (I) complexes which have been characterized using spectroscopic methods and X ray diffraction. Both gold (I) complexes and phosphines-phosphoniums have been studied in biology and these compounds turned out to be cytotoxic i…
Excitation energy dependence of fragment-mass distributions from fission of 180,190 Hg formed in fusion reactions of 36 Ar + 144,154 Sm
2015
Physics letters / B 748, 89 - 94 (2015). doi:10.1016/j.physletb.2015.06.068