Abstract The fluorination of a diversity of functionalized aryl iodides is readily achieved by silver fluoride in the presence of a cationic copper complex.The reaction is proposed to proceed by C—F reductive elimination from an in situ generated aryl copper(III) fluoride.
We overview an approach to modeling and rendering architectural scenes from a sparse set of photographs. The approach is designed to require no special hardware and to produce real-time renderings on standard graphics hardware. The modeling method is an interactive photogrammetric modeling tool for recovering geometric models of architectural scenes from photographs. The tool is practical as an interactive method because it solves directly for architectural dimensions rather than for a multitude of vertex coordinates or depth measurements. The technique also determines the camera positions of the photographs, allowing the photographs to be taken from arbitrary unrecorded locations. The rendering method creates novel views of the scene based on the recovered model and the original photographs. A view-dependent texture mapping method allows all available image information to be used to produce the most photorealistic renderings. We focus on a number of results and applications of the method.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Selective methods for the functionalization of indoles and other nitrogen heterocycles would provide access to the core structures of many natural products and pharmaceuticals. Although there are many methods and strategies for the synthesis of substituted indoles or functionalization of the azole ring, strategies for the selective functionalization of the benzo-fused portion of the indole skeleton, particularly the 7-position, are less common. We report a one-pot, iridium-catalyzed, silyl-directed C-H borylation of indoles at the 7-position. This process occurs in high yield with a variety of substituted indoles, and conversions of the 7-borylindole products to 7-aryl-, 7-cinnamyl-, and 7-haloindoles are demonstrated. The Ir-catalyzed, silyl-directed C-H borylation also occurs with several other nitrogen heterocycles, including carbazole, phenothiazines, and tetrahydroquinoline. The utility of this methodology is highlighted by the one-pot synthesis of a member of the pyrrolophenanthridone class of alkaloid natural products.
A comparison of the physical properties of hyperbranched and dendritic macromolecules with linear polymers and the linear analogs of these 3-dimensional polymers is presented. It is found that thermal properties, such as glass transition temperature and degradation, are the same regardless of the macromolecular architecture but are very sensitive to the number and nature of chain end functional groups. However, other properties, such as solubility, melt viscosity, chemical reactivity, intrinsic viscosity were found to be very dependent on the macromolecular architecture.
Polyphosphate degradation and phosphate secretion were optimized in Escherichia coli strains overexpressing the E. coli polyphosphate kinase gene (ppk) and either the E. coli polyphosphatase gene (ppx) or the Saccharomyces cerevisiae polyphosphatase gene (scPPX1) from different inducible promoters on medium- and high-copy plasmids. The use of a host strain without functional ppk or ppx genes on the chromosome yielded the highest levels of polyphosphate, as well as the fastest degradation of polyphosphate when the gene for polyphosphatase was induced. The introduction of a hybrid metabolic pathway consisting of the E. coli ppk gene and the S. cerevisiae polyphosphatase gene resulted in lower polyphosphate concentrations than when using both the ppk and ppx genes from E. coli, and did not significantly improve the degradation rate. It was also found that the rate of polyphosphate degradation was highest when ppx was induced late in growth, most likely due to the high intracellular polyphosphate concentration. The phosphate released from polyphosphate allowed the growth of phosphate-starved cells; excess phosphate was secreted into the medium, leading to a down-regulation of the phosphate-starvation (Pho) response. The production of alkaline phosphatase, an indicator of the Pho response, can be precisely controlled by manipulating the degree of ppx induction. Copyright 1998 John Wiley & Sons, Inc.
In this work we deal with slow–fast autonomous dynamical systems. We initially define them as being modeled by systems of differential equations having a small parameter multiplying one of their velocity components. In order to analyze their solutions, some being chaotic, we have proposed a mathematical analytic method based on an iterative approach [Rossetto et al., 1998]. Under some conditions, this method allows us to give an analytic equation of the slow manifold. This equation is obtained by considering that the slow manifold is locally defined by a plane orthogonal to the tangent system's left fast eigenvector. In this paper, we give another method to compute the slow manifold equation by using the tangent system's slow eigenvectors. This method allows us to give a geometrical characterization of the attractor and a global qualitative description of its dynamics. The method used to compute the equation of the slow manifold has been extended to systems having a real and negative eigenvalue in a large domain of the phase space, as it is the case with the Lorenz system. Indeed, we give the Lorenz slow manifold equation and this allows us to make a qualitative study comparing this model and Chua's model. Finally, we apply our results to derive the slow manifold equations of a nonlinear optical slow–fast system, namely, the optical parametric oscillator model.
Abstract The first Ir‐catalyzed enantioselective allylation of trisubstituted allylic electrophiles has been developed. Through modification of the leaving group of allylic electrophiles, we found that trisubstituted allylic phosphates are suitable electrophiles for asymmetric allylation. The reaction of allylic phosphates with enol silanes derived from dioxinones gave allylated products in good yields with high enantioselectivities.
