Asymmetric Hydrogenation vs Transfer Hydrogenation in the Reduction of Cyclic Imines

A comparison between the two most common reduction approaches for obtaining chiral amines, asymmetric hydrogenation (AH) versus asymmetric transfer hydrogenation (ATH), was accomplished by using iridium complexes based on atropoisomeric diphosphines and cyclic diamines as ligands respectively. Seven substrates, different in electronic and steric properties, were screened applying both reduction methods. For AH the best results in terms of enantioselectivity (e.e. up to 64%) were obtained by using [Ir(COD)(TetraMe-BITIOP)]Cl in the presence of DCDMH as additive. ATH was carried out with [IrCp*(CAMPY)Cl]Cl as catalyst, allowing the obtainment of the products with appreciable e.e. (up to 76%)

Asymmetric Hydrogenation of 1-aryl substituted-3,4-Dihydroisoquinolines with Iridium Catalysts Bearing Different Phosphorus-Based Ligands

Starting from the chiral 5,6,7,8-tetrahydroquinolin-8-ol core, a series of amino-phosphorusbased ligands was realized. The so-obtained amino-phosphine ligand (L1), amino-phosphinite (L2) and amino-phosphite (L3) were evaluated in iridium complexes together with the heterobiaryl diphosphines tetraMe-BITIOP (L4), Diophep (L5) and L6 and L7 ligands, characterized by mixed chirality. Their catalytic performance in the asymmetric hydrogenation (AH) of the model substrate 6,7-dimethoxy-1-phenyl-3,4-dihydroisoquinoline 1a led us to identify Ir-L4 and Ir-L5 catalysts as the most eective. The application of these catalytic systems to a library of dierently substituted 1-aryl-3,4-dihydroisoquinolines aorded the corresponding products with variable enantioselective levels. The 4-nitrophenyl derivative 3b was obtained in a complete conversion and with an excellent 94% e.e. using Ir-L4, and a good 76% e.e. was achieved in the reduction of 2-nitrophenyl derivative 6a using Ir-L5

On the relation between carbonyl stretching frequencies and the donor power of chelating diphosphines in nickel dicarbonyl complexes

The relation between spectroscopic observables and the detailed metal- ligand bonding features in chelation complexes is addressed using both experimental and state-of-the-art theoretical and computational methods. We synthesized and characterized a set of six nickel dicarbonyl complexes of general formula [Ni(CO)(2)(PP)], where PP is an atropoisomeric chelating diphosphine ligand. The analysis of the obtained experimental data and the basicity and oxidative potentials of the free ligands suggests a close relation between the donor ability of the chelating ligand and the carbonyl stretching frequencies observed in the complexes. We then use theory to unravel the detailed mechanisms of chelation-bond formation in terms of partial charge flows between the molecular orbitals of the fragments. By extending the promising, recently published natural orbitals for chemical valence/ charge displacement (NOCV/CD) analysis scheme we provide a thorough, quantitative description of the several charge fluxes following the metal-ligand bond formation and demonstrate that the carbonyl stretching frequencies in the considered complexes selectively respond to the sigma-donation charge flow from the phosphorus lone pairs of the ligands, with the frequency shift being in quantitative correlation with the extent of the ligand-to-metal charge transfer

Intersection Logic in sequent calculus style

The intersection type assignment system has been designed directly as deductive system for assigning formulae of the implicative and conjunctive fragment of the intuitionistic logic to terms of lambda-calculus. But its relation with the logic is not standard. Between all the logics that have been proposed as its foundation, we consider ISL, which gives a logical interpretation of the intersection by splitting the intuitionistic conjunction into two connectives, with a local and global behaviour respectively, being the intersection the local one. We think ISL is a logic interesting by itself, and in order to support this claim we give a sequent calculus formulation of it, and we prove that it enjoys the cut elimination property.Comment: In Proceedings ITRS 2010, arXiv:1101.410

Cascade Reaction by Chemo- and Biocatalytic Approaches to Obtain Chiral Hydroxy Ketones and anti 1,3-Diols

Achemo- andbiocatalytic cascade approach was applied for the stereos elective synthesis of hydroxy ketone sand the corresponding 1,3-diols. A new class of tridentate N,N,Oligands was used with coppe r(II) complexes for the asymmetric b-borylation of a, b-unsaturated compounds. The complex containing ligand L5 emergedas the best performer,and it gave the orga-noborane derivatives with good ee values. The corresponding keto\u2013alcohol compounds were then bioreduced by yeasts. The biotransformation set up with Rhodo Torula rubra allowed (R)- keto\u2013 alcohols and (S, S)-diols to be obtained with up to 99% ee and up to 99% de in favor of the anti enantiomers

Infaunal Marsh Foraminifera From the Outer Banks, North Carolina, USA

The distribution and abundance of live (rose Bengal stained) and dead, shallow infaunal (0–1 cm depth) and deep infaunal (\u3e1 cm depth) benthic foraminifera have been documented at three locations representing different salinity settings on the fringing marshes along the Pamlico Sound and Currituck Sound coasts of North Carolina’s Outer Banks. Two cores taken at each site represent the lower and higher marsh. Twenty-two taxa were recorded as live. Of these, eight taxa were found only at shallow infaunal depths; the other 14 taxa occur at deep infaunal depths in one or more cores. Only Jadammina macrescens and Tiphotrocha comprimata were recorded as living in all six cores. The distributions of the other taxa were restricted by combinations of infaunal depth, salinity regime and location on the marsh. The tests of infaunal foraminifera were generally more likely to be preserved in the lower marsh than the higher marsh at low- and intermediate-salinity sites. The opposite pattern was evident at the high-salinity site but this may be due to the low numbers of deep infaunal specimens recovered. Arenoparrella mexicana, Haplophragmoides wilberti, Jadammina macrescens and Trochammina inflata are the most resistant taxa, whereas Miliammina fusca is the species whose tests are most likely to be lost to post-mortem degradation. In five of the six cores, foraminiferal assemblages and populations do not differ significantly with depth which suggests that the foraminifera of the 0–1 cm depth interval provide an adequate model upon which paleoenvironmental (including former sea level) reconstructions can be based

Estació fotogramètrica digital per a pràctiques de generació cartogràfica

El mètode fotogramètric permet extreure informació mètrica del terreny a partir de mesures fetes sobre fotografies. La generació de la cartografia i dels plànols de les façanes dels edificis són exemples on s’utilitzen majoritàriament la fotogrametria com a eina de mesura. En aquest projecte es vol implementar una estació fotogramètrica que permeti construir el bloc de fotografies, que faci les correccions dels errors sistemàtics i que finalment permeti construir un model tridimensional de l’objecte en estudi, sigui el terreny, un edifici o qualsevol altre objecte físic. La intenció és que pugui executar-se sobre el sistema operatiu Windows instal·lat en ordinadors convencionals, tant els que disposa l’escola a la sala de càlcul com els ordinadors personals de cada estudiant.Peer Reviewe