Unusual regioselective intramolecular Diels-Alder reaction forming tricyclo[4.3.1.0(3,7)]decane system

The intramoleculae Diels-Alder reaction of cyclohexenone having an unsaturated ester side chain afforded tricyclo[4.3.1.0(3,7)]decanone in both a regio- and stereoselective manner under TMSCl-NEt(3)-ZnBr(2) conditions. Unexpectedly, the regiochemical control was against the conventional orbital requirement.     

Ising quantum Hall ferromagnet in magnetically doped quantum wells

We report on the observation of the Ising quantum Hall ferromagnet with Curie temperature T(C) as high as 2 K in a modulation-doped (Cd,Mn)Te heterostructure. In this system field-induced crossing of Landau levels occurs due to the giant spin-splitting effect. Magnetoresistance data, collected over a wide range of temperatures, magnetic fields, tilt angles, and electron densities, are discussed taking into account both Coulomb electron-electron interactions and s-d coupling to Mn spin fluctuations. The critical behavior of the resistance "spikes" at T-->T(C) corroborates theoretical suggestions that the ferromagnet is destroyed by domain excitations.     

Crystal structure of 5-benzoylamino-5-isopropyl-4-oxo-1,3-dioxane

C₁₄H₁₇NO₄ crystallizes in the monoclinic space groupP2₁/n (Z=4) witha=10.208(2),b=10.888(2),c=11.909(2) Å, and=90.89(2)°. The structure was solved by direct methods and refined by full-matrix LSQ to anR factor of 0.036. The 4-oxo-1,3-dioxane ring is in a slightly distorted O(1)-sofa conformation flattened at the C(4) end with the 5-isopropyl substituent in a pseudoaxial position and planar lactone group. The molecules form dimers by means of intermolecular N-HO(4) hydrogen bonds of 3.091(2) Å. The¹H NMR spectrum of the title compound shows unusual features.     

A direct electrochemical route to construct a polymer/manganese oxide layered structure

A layered nanocomposite with poly(diallyldimethylammonium), PDDA, intercalated between manganese oxide layers can be formed on a platinum electrode in a thin film form through a direct electrochemical route. The process involves a potentiostatic oxidation of aqueous Mn(2+) precursors in the presence of PDDA by applying a constant potential (+1.0 V vs Ag/AgCl).     

Template polymerization of columnar architectures based on the salts of a carboxylic acid and 2-amino alcohols: application to the molecular recognition of 2-amino alcohols

The salts of trialkoxybenzoic acids and 2-amino alcohols showed a columnar liquid crystalline phase; in the case of the salt of a polymerizable acid and norephedrine, the photopolymerization proceeded efficiently in the liquid crystalline state, and the resultant solid adsorbed 2-amino alcohols size, regio-, and enantio-selectively.     

Monotonicity and best approximation in Orlicz-Sobolev spaces with the Luxemburg norm

Criteria for strict monotonicity, upper (lower) locally uniform monotonicity and uniform monotonicity of Orlicz-Sobolev spaces with the Luxemburg norm are given. Some applications to best approximation are presented.     

Resonant scattering in the presence of strong laser fields

Resonant scattering in the presence of strong laser fields is investigated by solving numerically the one-dimensional Schrödinger equation. It is shown that at high intensities of radiation one can observe new effects in free-free transitions like, for instance, the splitting and overlapping of the scattering resonances. The relation of these phenomena to multiphoton ionisation processes is also discussed. The Schrödinger equation is solved by applying the approach proposed by Jung and Taylor [1] or by Varró and Ehlotzky [34]. It is also shown how the second approach can be generalised in order to treat more complicated problems like for instance the relativistic processes.     

The design, synthesis, and application of a chiral coupling reagent derived from strychnine for the enantioselective activation of a carboxylic group

The concept of a chiral coupling reagent for the enantioselective synthesis of peptides with a predictable configuration and enantiomeric purity from racemic substrates is presented. The reagent was prepared by treatment of strychninium tetrafluoroborate with 2-chloro-4,6-dimethoxy-1,3,5-triazine in the presence of sodium bicarbonate yielding N-(4,6-dimethoxy-1,3,5-triazin-2-yl)strychninium tetrafluoroborate in high yield, which is stable at room temperature, and in a broad range of solvents gave enriched Z-Ala-Phe-OMe (dr from 95/5 to 60/40) in high yield with d-configuration on the alanine residue starting from rac-Z-Ala-OH.