Enantioselective olefin epoxidation using novel biphenyl and binaphthyl azepines and azepinium salts

Homologous biphenyl and (diastereomeric) binaphthyl tertiary azepines and quaternary iminium salts were prepared from (S)- and (R)-3,3-dimethylbutan-2-amine. Both the amines and iminium ions behave as effective catalysts for the enantioselective epoxidation of unfunctionalized olefins (ee up to 87%).     

Trifluoromethylated amino alcohol as chiral auxiliary for highly diastereoselective and fast Simmons–Smith cyclopropanation of allylic amine

Three advantages of a trifluoromethylated amino alcohol auxiliary in the Simmons–Smith cyclopropanation of allylic amines are described. The trifluoromethylated amino alcohol auxiliary reduces unwanted side reactions induced by its acidic, and thus less nucleophilic, hydroxy group. The auxiliary accelerated the reaction rate by its electron-withdrawing effect, and promoted the reaction with excellent diastereoselectivity.     

12-Ring Network Coordination Polymer——{[Cu(C_4N_2H_(10))_4]_2·H_4V_4O_(14)}_n Formed by Linking cyclo-[H_4V_4O_(14)]~(4-) with Cu(C_4N_2H_(10))~(2+)_4 Cation Clusters

IntroductionThe interest in polyoxometalates that are widelyused in medical chemistry, catalyst reactions, and ma-terial sciences stems from their complicated aggregatesformed by means of corner-, edge- and face-sha-ring[1—4]. The exploitation of new str…     

The measurement of beta asymmetries at UNISOR/NOF using external plastic scintillator detectors

The performance of two external plastic scintillator detectors has been tested in an off-line mode using a source of¹⁰⁶RuFe at UNISOR/NOF. The measurement of beta asymmetries at various temperatures has resulted in the reproduction of the previously-determined magnetic dipole moment for the 1⁺ ground state of¹⁰⁶Rh and in addition the conclusion that the sign of this moment is positive.     

A transportable gamma spectroscopy system applied to the measurement of fission products

Normally, gamma-ray spectroscopy is performed by equipment positioned in the SLOWPOKE-2 Facility at the Royal Military College; however, there have occasionally been requirements for analyses externally. A transportable gamma spectroscopy system was thus assembled by acquiring a commercially available multichannel analyzer, analysis program and detector, and by designing and constructing a transportable shielding castle. It was then used to take measurements of fission product concentrations at several research reactors.     

Geochemical and physical analysis of the bedrock formations and lowest tills at the Wellsch Valley Site,Saskatchewan, Canada

Nine bedrock and two till samples were analyzed to determine whether their chemical and physical properties could be used to distinguish between bedrock units and to differentiate local bedrock from overlying tills. The bedrock samples came from The North Cliff subsite of the Wellsch Valley Site, and the till samples from Jaw Face subsite. Eight of the nine bedrock samples show great similarity. However, their geochemical differences from the overlying Quaternary tills establish that the tills contain much material entrained, during one or more early Quaternary glaciations, from older bedrock outcrops to the north and northeast. The glaciers that laid down the tills appear to have reworked and concentrated elements compatible with a dry climate, probably formed by weathering during long interglacial, and perhaps preglacial, intervals when the surface was undergoing slow degradation.     

Control of calcium carbonate crystallization utilizing amphiphilic block copolypeptides

Control over the morphology of calcium carbonate (CaCO₃) crystals has been achieved through the use of anionic, amphiphilic block copolypeptides during crystallization. Microspheres of CaCO₃ can be synthesized by the introduction of preformed organic, amphiphilic block copolypeptide templates, poly(l-aspartate sodium salt)₁₀₀-block-[poly(l-phenylalanine)₂₅-random-(l-leucine)₂₅] (1) and poly(l-glutamate sodium salt)₁₀₀-block-[poly(l-phenylalanine)₂₅-random-(l-leucine)₂₅] (2). When cationic amphiphiles are used in lieu of the anionic amphiphiles, only CaCO₃ rhombohedra are produced. The self-assembling amphiphile controls the precipitation of the microspheres by acting as a template to form giant CaCO₃ microspheres. These microspheres are composed of nanocrystals ranging in size from 10 to 60 nm using 1 and 20 to 100 nm using 2.