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Abstract We report the regioselective and enantioselective formal hydroamination of unsymmetrical internal alkenes catalyzed by a copper catalyst ligated by DTBM‐SEGPHOS. The regioselectivity of the reaction is controlled by the electronic effects of ether, ester, and sulfonamide groups in the homoallylic position. The observed selectivity underscores the influence of inductive effects of remote substituents on the selectivity of catalytic processes occurring at hydrocarbyl groups, and the method provides direct access to various 1,3‐aminoalcohol derivatives with high enantioselectivity.
Abstract Geostatistical techniques are being used increasingly to model reservoir heterogeneity on multiple scales. Several techniques are now available which differ in their underlying assumptions, complexity and applications. This paper compares the geostatistical sequential gaussian, sequential indicator, and truncated gaussian simulation techniques with the more traditional geological hand mapping description technique and compares their influence on flow simulation performance. The base geological description was generated using a hand drawn map of the geological facies associations within a 3-D model area in a fluvio-deltaic environment. The average values of porosity and permeability were assigned to the respective facies associations. A second description was generated using sequential gaussian simulation by honoring the porosity and permeability well data, the corresponding vertical variograms, and the inferred lateral variograms. A third description was generated using sequential indicator simulation to distribute porosity and permeability instead of sequential gaussian simulation. Both of these simple geostatistical descriptions were not constrained by explicit geological facies association information. A final more complex geostatistical description was generated in which the underlying geological framework of facies association was first simulated using truncated gaussian simulation and then the porosity and permeability were distributed within each facies association using sequential gaussian simulation. All of the fine scale descriptions were compared in detail and scaled up to large grid blocks appropriate for flow simulation using a pressure solver. A comparison of the 3-D hand drawn facies association map with the one computed using truncated gaussian simulation showed that the hand drawn map contained less variations than the geostatistical facies association map when conditioned to the same well data. Comparison of the fine scale porosity and permeability maps showed that the distribution of the average values of porosity and permeability in the 3-D hand drawn facies association map failed to reproduce the complex texture of the rocks giving a considerably more uniform distribution of these attributes. It was found that distributing porosity and permeability geostatistically without the influence of explicit facies association information significantly reduced the effective control on the distribution of these attributes, resulting in a more continuous distribution of porosity and permeability than that obtained when facies association information was used. Comparison of the fine scale permeability distributions to those obtained after scaleup showed that the pressure solver maintained the major permeability features apparent in the fine scale distribution which were important to reservoir performance. The influence of these description techniques on reservoir performance was compared using a fluid flow simulator.
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Pd source matters: A general method for palladium-catalyzed α-arylation of aldehydes (see scheme) was developed to couple linear and branched aldehydes with electron-poor and electron-rich bromo- and chloroarenes. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2008/z705357_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.
Although healthy dentin is invariably hydrated in vivo, from a perspective of examining the mechanisms of fracture in dentin, it is interesting to consider the role of water hydration. Furthermore, it is feasible that exposure to certain polar solvents, e.g., those found in clinical adhesives, can induce dehydration. In the present study, in vitro deformation and fracture experiments, the latter involving a resistance-curve (R-curve) approach (i.e., toughness evolution with crack extension), were conducted in order to assess changes in the constitutive and fracture behavior induced by three common solvents - acetone, ethanol and methanol. In addition, nanoindentation-based experiments to evaluate the deformation behavior at the level of individual collagen fibers and ultraviolet Raman spectroscopy to evaluate changes in bonding were performed. The results indicate a reversible effect of chemical dehydration, with increased fracture resistance, strength, and stiffness associated with lower hydrogen bonding ability of the solvent. These results are analyzed both in terms of intrinsic and extrinsic toughening phenomena to further understand the micromechanisms of fracture in dentin and the specific role of water hydration.