Primjena iskustava biološke fizike u savremenom ribarstvu

The EPSRC doctoral training grant supported RP (DTG grant: 1518070)). The EPSRC (EP/M003868/1) is also acknowledged for funding (JAF&PD).The scope of carbon monoxide-free Asymmetric Transfer HydroFormylation (ATHF) procedures using a highly active single catalyst system derived from 1,2-bis-((2,5)-diphenylphospholano)ethane as chiral ligand has been studied. This reveals some highly successful reactions, but also significant limitations. The development of a new protocol in which a catalyst for formaldehyde decomposition to CO and H2 is combined with the catalyst of choice for the subsequent asymmetric hydroformylation is described. This enables ATHF reactions that were problematic to be significantly improved. The new method has been used in the synthesis of several key precursors to biologically active molecules.PostprintPeer reviewe

A ruthenium-based catalytic system for a mild borrowing-hydrogen process

The alkylation of arylamines using stoichiometric amounts of aliphatic and benzylic alcohols in the presence of tBuOK was carried out at 55 °C using a low catalyst loading of [Ru(cod)-Cl2]n/PTA (1,3,5-triaza-7-phosphaadamantane). The overall borrowing-hydrogen process does not require a controlled nitrogen atmosphere, and it could also be carried out at room temperature using higher loading of base. A wide range of substrates can be used in this transformation, and it has a good tolerance of different substituents. This catalytic system proved also to be efficient for other hydrogen-transfer reactions such as a tandem oxidation/C-C coupling between 1-phenylethanol and primary alcohols

Rhenium Allenylidenes and Their Reactivity toward Phosphines: A Theoretical Study

Density functional and local MP2 calculation shave been performed to study the electronic structure of the rhenium(I)allenylidene [(triphos)(CO)2Re(=C=C=CRR )] species[triphos=MeC(CH2PPh2)3;R, R =aryl group] and its reactivity toward tertiary phosphines. The calculated electronic structure shows a relatively electron-rich nature of the[(triphos)(CO)2Re] synthon in agreement with the experimental behavior of the corresponding allenylidene complex [(triphos)(CO)2Re(=C=C=CPh2)] (R=R =Ph). Both the kinetics and the thermodynamics of the nucleophilic addition of tertiary phosphines PMe3-xPhx (x=0,1,2, and 3) have been considered. The results indicate lower activation energies for the phosphine attack to Cγ, which leads, however, to products higher in energy than those of the attack to CR. The computed behavior agrees with the experimental evidence showing that the products of the attack to Cγ are kinetically favored, while the products of the attack to CR are thermodynamically favored. Finally, we addressed the mechanism of phosphine migration from Cγ to CR, finding a low-energy path corresponding to an incomplete detachment of the phosphine moiety that then shifts from the Cγ to the CR atoms while remaining weakly bound to the allenylidene unit

Borane adducts of the water soluble phosphine PTA (PTA=1,3,5-triaza-7-phosphaadamantane)

Boronation of the water soluble phosphine PTA (PTA= 1,3,5-triaza-7-phosphaadamantane) in dry THF easily affords the N-boronated adduct N-B-PTABH(3) which represents the first N-coordinated adduct of this popular water soluble phosphine (N-B-PTABH3= 1-boranyl-1,3,5-triaza-7-phosphadamantane). In situ P-31 NMR spectroscopy suggests the Occurrence of a stepwise boronation resulting in the addition of as many as four equivalents of BH3 to PTA to give the polyboranyl species N-x, P-y-B-PTA(BH3)((x+y)) (x= 1-3, y= 0,1). Hydrolysis of the monoboranyl adduct occurs slowly in the presence of water yielding back PTA and boric acid, H3BO3. (c) 2006 Elsevier B.V. All rights reserved

Electron-Poor Rhenium Allenylidenes and Their Reactivity toward Phosphines: A Combined Experimental and Theoretical Study

The reactionof 1-(phenyl)-1-(p-nitrophenyl)-2-propyn-1-ol with the Re(I) precursor [(triphos)(CO)2Re(OTf)] in dichloromethane at 0 °C afforded the cationic allenylidene complex [(triphos)(CO)2Re{C=C=C(C6H5)(p-C6H4NO2)}]+ (3) as a dark burgundy red triflate salt after solvent evaporation. The reaction of 3 with 1.2 equiv of the phosphine PMePh2 at −40 °C led first to the γ-phosphonio alkynyl complex [(triphos)(CO)2Re{CCCPh(p-C6H4NO2)(PMePh2)}]+ (5) (observed as a pair of distinct rotamers, 5a, b) and then, on slow increase of the temperature to 0 °C, to the α-phosphonioallenyl complex [(triphos)(CO)2Re{C(PMePh2)=C=Ph(p-C6H4NO2)}]+ (6). On the other hand, the reaction of 3 with the more nucleophilic PMe3 at −60 °C led to its complete transformation into a compound, suggested to be the α-phosphonioallenyl derivative[(triphos)(CO)2Re{C(PMe3)=C=C(C6H5)(p-C6H4NO2)}]+ (7). To study the effect due to the strongly electron withdrawing p-nitrophenyl substituent on the allenylidene geometry, electronic structure, and reactivity with phosphines, we performed theoretical calculations on 3 and other hypothetical p-nitro-substituted allenylidenes as well as on the products and plausible intermediates of its reaction with PMe3 and PMePh2. Finally, theoretical methods were applied to shed light on the nature of the two rotamers observed for the γ-phosphonio alkynyl complex 5

«Water soluble PTA-complexes and their catalytic applications under water-biphasic conditions»

International audienceno abstrac

«Sustainable chemistry with water soluble phosphines: the enlightening story of PTA as an environmental friendly ligand»

International audienceno abstrac

Lower- and upper-rim-modified derivatives of 1,3,5-triaza-7-phosphaadamantane: Coordination chemistry and applications in catalytic reactions in water

International audienceno abstrac