Amination of ethers using chloramine-T hydrate and a copper(I) catalyst

Amination of C-H bonds activated by ether oxygen atoms is facile with chloramine-T as nitrene source and copper(I) chloride in acetonitrile as catalyst. For cyclic ethers the hemiaminal products are generally stable and can be isolated pure. For acyclic ethers, the hemiaminal products, as expected, fragment with elimination of alcohol to yield imines. When activation of benzylic positions is remote through a conjugated system, stable benzylamine derivatives are isolated. Mechanistic studies are consistent with concerted insertion of an electrophilic nitrenoid into the C-H bond in the rate-determining step, though in an asynchronous manner with a more activated substrate.     

Preparation and Ferroelectric Properties of YMnO3 Thin Films with c-Axis Preferred Orientation by the Sol-Gel Method

Hexagonal YMnO₃ has a ferroelectric property with an optimal remanent polarization along the c-axis. The c-axis oriented YMnO₃ thin films with a small leakage current were prepared by the sol-gel dipping method. The c-axis orientation of the films was promoted by the addition of diethanolamine to the Mn precursor solution. A heat treatment with multiple steps led to a dense film structure with fine grains. The dense structure resulted in the decrease of the leakage current. Furthermore, when the films were heat-treated in a vacuum, the leakage current became considerably small and the ferroelectricity of the YMnO₃ thin films was observed even at room temperature.     

Total synthesis of optically active lycopladine A by utilizing diastereoselective protection of carbonyl group in a 1,3-cyclohexanedione derivative

We successfully synthesized two enantiomers of bicyclic enones, (7R,7aR)- and (7S,7aS)-9, from the hemiacetal 2a, which we first synthesized from the symmetrical diketone 1a via diastereoselective carbon-oxygen bond formation between one of the carbonyl groups and the chiral alcohol on the C2 side chain in a 2,2-disubstituted 1,3-cycloalkanedione derivative. We also report the total synthesis of natural (+)-lycopladine A [(+)-6] from (7R,7aR)-9 and the formal synthesis of unnatural (-)-lycopladine A [(-)-6] from (7S,7aS)-9.     

Structural identification of uric acid and its monohydrates by IR-UV double resonance spectroscopy

We have employed IR-UV double resonance spectroscopy to identify the tautomeric and isomeric structures of uric acid and its monohydrated clusters which are produced by the techniques of laser-desorption and supersonic-jet cooling. The IR spectrum obtained for bare uric acid exhibits four distinct NH stretching transitions assignable to those of the most stable triketo form. We have also observed the two most stable monohydrated clusters, each with uric acid in the triketo form and water bonded to either the N3H or N9H site. It is demonstrated that the R2PI spectra of these monohydrates can be separated by using the IR-purified spectroscopic method.     

Pushing exercise program to correct glottal incompetence

A voice therapy program using pushing exercises to correct glottal incompetence is described. The program utilizes various types of instrumentation to determine whether or not a given patient is likely to benefit from the treatment. The program also provides feedback of target voices. Three cases with incomplete glottal closure and subsequent vocal dysphonia characterized by an asthenic breathy quality are used to illustrate the program. Details of the program, termination criteria, and problems and precautions learned from treating 29 patients over a 3-year period are presented.     

Palladium-catalyzed stereospecific 1,4-hydrogen migration of cis-cyclohex-2-en-1,4-diol systems

It has been revealed that the generation of 2-cyclohexenones from cis-1,4-dihydroxycyclohexene derivatives under PdCl₂(PPh₃)₂-HCO₂NH₄ system takes place in an intramolecular pathway involving unprecedented mode of suprafacial 1,4-hydrogen migration across the 1,4-allylic centers.     

Stability problems for Cantor stochastic differential equations

We consider driftless stochastic differential equations and the diffusions starting from the positive half line. It is shown that the Feller test for explosions gives a necessary and sufficient condition to hold pathwise uniqueness for diffusion coefficients that are positive and monotonically increasing or decreasing on the positive half line and the value at the origin is zero. Then, stability problems are studied from the aspect of Hölder-continuity and a generalized Nakao–Le Gall condition. Comparing the convergence rate of Hölder-continuous case, the sharpness and stability of the Nakao–Le Gall condition on Cantor stochastic differential equations are confirmed. Furthermore, using the Malliavin calculus, we construct a smooth solution to degenerate second order Fokker–Planck equations under weak conditions on the coefficients.     

Regiocontrolled intramolecular cyclizations of carboxylic acids to carbon-carbon triple bonds promoted by acid or base catalyst

We systematically investigated, for the first time, the relationship between regioselectivity and acid/base effects in the cyclization reactions between carboxylic acids and carbon-carbon triple bonds. We found novel acid- and base-promoted cyclizations to selectively give isocoumarin or pyran-2(2H)-one and phthalide or furan-2(5H)-one skeletons, respectively, and established a catalytic version of regioselective heterocyclic ring synthesis. Density functional theory calculations and application to a short route to thunberginol A were also described. [reaction: see text].