Chain walking of allylrhodium species towards esters during rhodium-catalyzed nucleophilic allylations of imines

Allylrhodium species derived from δ-trifluoroboryl β,γ-unsaturated esters undergo chain walking towards the ester moiety.The resulting allylrhodium species react with imines to give products containing two new stereocenters and a Z-alkene. By using a chiral diene ligand, products can be obtained with high enantioselectivities, where a pronounced matched/mismatched effect with the chirality of the allyltrifluoroborate is evident

Optical absorption of BaF[2] crystals with different prehistory when irradiated by high-energy electrons

The spectra of stable optical absorption of BaF[2] crystals containing uncontrollable impurities after irradiation with 3 MeV electrons are studied at room temperature. The dependence of the efficiency of stable color accumulation in the region of emerging cross-luminescence on the absorption coefficients measured near the fundamental absorption edge in unirradiated crystals of various prehistory is traced

Mathematical modelling of energy conversion of pulsed electron beam in BaF[2] crystal

This paper presents the results of mathematical modeling of spatiotemporal distribution of energy in a BaF[2] crystal in an area of dissipation of energy of an pulsed electron beam. Fluence is varied from 0.188 to 0.626 J/cm{2}. Electron beam pulse duration was 24 ns, and the maximum electron energy of 280 KeV. Based on the obtained of energy distributions temperature change of the material during irradiation were calculated

Remote nucleophilic allylation by allylrhodium chain walking

Metal migration through a carbon chain is a versatile method for achieving remote functionalization. However, almost all known examples involve the overall net migration of alkylmetal species. Here, we report that allylrhodium species obtained from hydrorhodation of 1,3-dienes undergo chain walking toward esters, amides, or (hetero)arenes over distances of up to eight methylene units. The final, more highly conjugated allylrhodium species undergo nucleophilic allylation with aldehydes and an imine to give Z-homoallylic alcohols and amines, respectively

The influence of nickel layer thickness on microhardness and hydrogen sorption rate of commercially pure titanium alloy

The influence of nickel coating thickness on microhardness and hydrogen sorption rate by commercially pure titanium alloy was established in this work. Coating deposition was carried out by magnetron sputtering method with prior ion cleaning of surface. It was shown that increase of sputtering time from 10 to 50 minutes leads to increase coating thickness from 0.56 to 3.78 ?m. It was established that increase of nickel coating thickness leads to increase of microhardness at loads less than 0.5 kg. Microhardness values for all samples are not significantly different at loads 1 kg. Hydrogen content in titanium alloy with nickel layer deposited at 10 and 20 minutes exceeds concentration in initial samples on one order of magnitude. Further increasing of deposition time of nickel coating leads to decreasing of hydrogen concentration in samples due to coating delamination in process of hydrogenation

The influence of nickel layer thickness on microhardness and hydrogen sorption rate of commercially pure titanium alloy

The influence of nickel coating thickness on microhardness and hydrogen sorption rate by commercially pure titanium alloy was established in this work. Coating deposition was carried out by magnetron sputtering method with prior ion cleaning of surface. It was shown that increase of sputtering time from 10 to 50 minutes leads to increase coating thickness from 0.56 to 3.78 ?m. It was established that increase of nickel coating thickness leads to increase of microhardness at loads less than 0.5 kg. Microhardness values for all samples are not significantly different at loads 1 kg. Hydrogen content in titanium alloy with nickel layer deposited at 10 and 20 minutes exceeds concentration in initial samples on one order of magnitude. Further increasing of deposition time of nickel coating leads to decreasing of hydrogen concentration in samples due to coating delamination in process of hydrogenation

Light-stable silver N-Heterocyclic carbene catalysts for the alkynylation of ketones in air

The authors gratefully acknowledge the Royal Society (University Research Fellowship to C.S.J.C) for funding.N-Heterocyclic carbene (NHC) silver(I) complexes were efficiently employed in the alkynylation of ketones. These cationic complexes were found highly active and efficient under mild conditions without the need of additive, and in air. The mechanism of this transformation was investigated. Experiments suggest the formation of a silver-acetylide key intermediate and the release of one ligand from the silver centre enabling the transformation.PostprintPeer reviewe