Enantioselective conjugate allylation of cyclic enones

Enantioselective organocatalytic 1,2-allylation of a cyclic enone followed by anionic oxy-Cope rearrangement delivered the ketone as a mixture of diastereomers. This appears to be a general method for the net enantioselective conjugate allylation of cyclic enones.     

Practical Enzymatic Production of Carbocycles

The Pd-catalyzed carbon-carbon bond formation pioneered by Heck in 1969 has dominated medicinal chemistry development for the ensuing fifty years. As the demand for more complex three-dimensional active pharmaceuticals continues to increase, preparative enzyme-mediated assembly, by virtue of its exquisite selectivity and sustainable nature, is poised to provide a practical and affordable alternative for accessing such compounds. In this minireview, we summarize recent state-of-the-art developments in practical enzyme-mediated assembly of carbocycles. When appropriate, background information on the enzymatic transformation is provided and challenges and/or limitations are also highlighted.     

Predicting the solubility of xenon in n-hexane and n-perfluorohexane: a simulation and theoretical study

The solubility of xenon in n-hexane and n-perfluorohexane has been studied using both molecular simulation and a version of the SAFT approach (SAFT-VR). The calculations were performed close to the saturation line of each solvent, between 200 K and 450 K, which exceeds the smaller temperature range where experimental data are available in the literature. Molecular dynamics simulations, associated with Widom's test particle insertion method, were used to calculate the residual chemical potential of xenon in n-hexane and n-perfluorohexane and the corresponding Henry's law coefficients. The simulation results overestimate the solubility of xenon in both solvents when simple geometric combining rules are used, but are in good agreement if a binary interaction parameter is included. With the SAFT-VR approach we are able to reproduce the experimental solubility for xenon in n-hexane, using simple Lorentz-Berthelot rules to describe the unlike interaction. In the case of n-perfluorohexane as a solvent, a binary interaction parameter was introduced, taken from previous work on (xe + C₂F₆) mixtures. Overall, good agreement is obtained between the simulation, theoretical and experimental data.     

Laplace–Beltrami enhancement for unstructured two-dimensional meshes having dendritic elements and boundary node movement

The Laplace–Beltrami mesh enhancement algorithm of Hansen et al. ,  and  has been implemented and broadened to include meshes containing dendritic elements and allowing for boundary node movement. This implementation operates on an unstructured two-dimensional mesh by forming an equivalent weak statement using finite element interpolation, assembly, and solution ideas to iteratively place those nodes allowed to move. Moving boundary nodes are constrained to follow the boundary geometry described as a Wilson–Fowler spline (e.g., [3, Section 2.1.3.1]). Implementation details concerning the element basis set modifications, the metric tensor for dendritic element treatment and boundary node movement are presented. Laplacian (e.g., [6]) enhancement is included as a special case. Results are presented which illustrate the algorithm for three test problems.     

Tautomerism in some quinaldyl sulfones

A series of quinaldyl sulfones was synthesized and their tautomeric composition was determined by ¹H nmr.     

Total synthesis of the ethyl ester of the major urinary metabolite of prostaglandin E(2)

The preparation of the ethyl ester of the major urinary metabolite of prostaglandin E(2) 3 is described. The key step is the kinetic opening of the TBS-protected bicyclic ketone 7 with thiophenol.     

Applications of the coherent state representation in the theory of magnetism: II. Helical spin configurations

In a previous paper, the coherent state representation of spin wave states was used to derive the low temperature expansion for the free energy of the Heisenberg model of a ferromagnet. In this paper, the same formalism is applied to anisotropic systems which are usually described semiclassically. The coherent state parameters are shown to be ideally suited for describing certain of the resulting helical spin configurations. The coherent state approach emphasizes the analogy of these states to superfluid boson systems. A model spin Hamiltonian appropriate to Erbium is chosen and discussed in this light. In particular, the transition in a transverse magnetic field from the ground state cone configuration to a fan configuration, the stability and possible metastability of these states and the fluctuations about them are investigated. Numerical estimates show at least qualitative agreement with experiment.