Edoardo Cesarotti

Bio: Edoardo Cesarotti is an academic researcher from University of Milan. The author has contributed to research in topics: Ruthenium & Enantioselective synthesis. The author has an hindex of 19, co-authored 71 publications receiving 1098 citations.

New Class of Chiral Diphosphine Ligands for Highly Efficient Transition Metal-Catalyzed Stereoselective Reactions: The Bis(diphenylphosphino) Five-membered Biheteroaryls.

Abstract: The synthesis and application of three examples of a new class of chiral (C2) atropisomeric diphosphines characterized by two interconnected five-membered heteroaromatic rings, with hindered rotation around the interanular bond, are described. Optically pure (+)- and (−)-2,2‘-bis(diphenylphosphino)-4,4‘,6,6‘-tetramethyl-3,3‘-bibenzo[b]thiophene (tetraMe-bitianp) (1a) and the parent unsubstituted system (+)- and (−)-bitianp (1b) were synthesized. They were found to be optically stable at 100 °C and were successfully employed as ligands in the Ru(II)-catalyzed hydrogenation of α- and β-oxo esters to the corresponding α- and β-hydroxy esters and in the hydrogenation of olefinic substrates. The optical and chemical yields were comparable with those reported for the same Ru(II)-binap-catalyzed reactions carried out under the same experimental conditions. The 2,2‘-bis(diphenylphosphino)-3,3‘-bibenzo[b]furan (1c), the oxygenated analogue of bitianp, was found to be configurationally unstable at room temperature....

2,2',5,5'-tetramethyl-4,4'-bis(diphenylphoshino)-3,3'-bithiophene: a new, very efficient, easily accessible, chiral biheteroaromatic ligand for homogeneous stereoselective catalysis

Abstract: The four-step straightforward synthesis of enantiopure (+)- and (−)-2,2‘,5,5‘-tetramethyl-4,4‘-bis(diphenylphoshino)-3,3‘-bithiophene (tetraMe-BITIOP), a new C2-symmetry chelating ligand for transition metals, is described, starting from 2,5-dimethylthiophene. The complexes of this electron-rich diphosphine with Ru(II) and Rh(I) were used as catalysts in some homogeneous hydrogenation reactions of prostereogenic carbonyl functions of α- and β-ketoesters, of prostereogenic carbon−carbon double bonds of substituted acrylic acids, and of N-acetylenamino acids. The enantiomeric excesses were found to be excellent in all the experiments and comparable with the best results reported in the literature for the same reactions, carried out under similar experimental conditions, with the metal complexes of the most popular chiral diphosphine ligands as catalysts.

(Diphenylphosphino)-biheteroaryls: the first example of a new class of chiral atropisomeric chelating diphosphine ligands for transition metal catalysed stereoselective reactions

Abstract: Ruthenium(II) dichloride complexes with (+)- and (–)-2,2′-bis(diphenylphosphino)-4,4′,6,6′-tetramethyl-3,3′-bibenzo[b]thiophene (1a), new chiral atropisomeric heterocyclic ligands, reduce α- and β-oxoesters to α- and β-hydroxyesters with an enantiomeric purity comparable, if not higher, to that reported for binap under the same experimental conditions.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Asymmetric Transition Metal-Catalyzed Allylic Alkylations.

Abstract: Efficient and reliable amplification of chirality has borne its greatest fruit with transition metal-catalyzed reactions since enantiocontrol may often be imposed by replacing an achiral or chiral racemic ligand with one that is chiral and scalemic While the most thoroughly developed enantioselective transition metal-catalyzed reactions are those involving transfer of oxygen (epoxidation and dihydroxylation)1,2 and molecular hydrogen,3 the focus of this review is on the area of enantioselective transition metal-catalyzed allylic alkylations which may involve C-C as well as C-X (X ) H or heteroatom) bond formation4-9 The synthetic utility of transitionmetal-catalyzed allylic alkylations has been soundly demonstrated since its introduction nearly three decades ago10-21 In contrast to processes where the allyl moiety acts as the nucleophilic partner, we will limit our discussion to processes which result in nucleophilic displacements on allylic substrates (eq 1) Such reactions have been recorded with a broad

New Chiral Phosphorus Ligands for Enantioselective Hydrogenation

Abstract: The increasing demand to produce enantiomerically pure pharmaceuticals, agrochemicals, flavors, and other fine chemicals has advanced the field of asymmetric catalytic technologies.1,2 Among all asymmetric catalytic methods, asymmetric hydrogenation utilizing molecular hydrogen to reduce prochiral olefins, ketones, and imines, have become one of the most efficient methods for constructing chiral compounds.3 The development of homogeneous asymmetric hydrogenation was initiated by Knowles4a and Horner4b in the late 1960s, after the discovery of Wilkinson’s homogeneous hydrogenation catalyst [RhCl(PPh3)3]. By replacing triphenylphosphine of the Wilkinson’s catalystwithresolvedchiralmonophosphines,6Knowles and Horner reported the earliest examples of enantioselective hydrogenation, albeit with poor enantioselectivity. Further exploration by Knowles with an improved monophosphine CAMP provided 88% ee in hydrogenation of dehydroamino acids.7 Later, two breakthroughs were made in asymmetric hydrogenation by Kagan and Knowles, respectively. Kagan reported the first bisphosphine ligand, DIOP, for Rhcatalyzed asymmetric hydrogenation.8 The successful application of DIOP resulted in several significant directions for ligand design in asymmetric hydrogenation. Chelating bisphosphorus ligands could lead to superior enantioselectivity compared to monodentate phosphines. Additionally, P-chiral phosphorus ligands were not necessary for achieving high enantioselectivity, and ligands with backbone chirality could also provide excellent ee’s in asymmetric hydrogenation. Furthermore, C2 symmetry was an important structural feature for developing new efficient chiral ligands. Kagan’s seminal work immediately led to the rapid development of chiral bisphosphorus ligands. Knowles made his significant discovery of a C2-symmetric chelating bisphosphine ligand, DIPAMP.9 Due to its high catalytic efficiency in Rh-catalyzed asymmetric hydrogenation of dehydroamino acids, DIPAMP was quickly employed in the industrial production of L-DOPA.10 The success of practical synthesis of L-DOPA via asymmetric hydrogenation constituted a milestone work and for this work Knowles was awarded the Nobel Prize in 2001.3k This work has enlightened chemists to realize * Corresponding author. 3029 Chem. Rev. 2003, 103, 3029−3069

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Abstract: : The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg