Synthesis of sulfonyloxy furoxans via hydroxyfuroxan ammonium salts

Furoxans are distinctive heteroaromatic compounds in that they are potentially capable of releasing nitric oxide under physiological conditions. In order to utilize the furoxan scaffold for the development of functional molecules, synthetically relevant functional groups are required for access to diverse furoxans. In this report, a facile route to furoxans with sulfonyloxy groups, which are halide surrogates, has been developed. The key features of this strategy include the synthesis and utilization of bench-stable hydroxyfuroxan salts, the use of sulfonyl anhydrides in the sulfonylation step instead of sulfonyl chlorides, and the photochemical isomerization of one regioisomer to another in order to gain access to both.     

Phosphazene Base tBu-P4 Catalyzed Methoxy–Alkoxy Exchange Reaction on (Hetero)Arenes

The organic superbase tBu-P4 catalyzes methoxy-alkoxy exchange reactions on (hetero)arenes with alcohols. The catalytic reaction proceeded efficiently with electron-deficient methoxy(hetero)arenes as well as with a variety of alcohols, including 3-amino-1-propanol, β-citronellol, menthol, and cholesterol. An intramolecular version of this reaction furnished six- and seven-membered ring compounds.     

Application of X-ray fluorescence holography to the analysis of the interior and surface of an yttrium oxide thin film

We report on the characterization of a thin film of yttrium oxide by X-ray fluorescence holography. The sample has a layered structure with an YO base layer and an oxidized Y₂O₃ surface. Both layers are clearly observed in the atomic image reconstructions, and their local structure is analyzed. We show that by using incident energies close to the absorption edge of the fluorescing atom, it becomes possible to observe the thin surface layer clearly, even next to a base layer containing the same fluorescing element.     

Radiation-Induced Solid-State Polymerization in Binary Systems. VI. Polymerization of Vinyl Compounds in the Supercooled Liquid Phase

Abstract

The radiation-induced polymerization of glass-forming systems containing vinyl monomers was investigated. Irradiation below the secondorder transition temperature (T_g) of the systems causes no in-source polymerization but does cause a very rapid postpolymerization in the course of heating above T_g. Differential thermal analysis was carried out to estimate T_g and to follow the postpolymerization.     

Rhodium/chiral diene-catalyzed asymmetric methylation of N-sulfonylarylimines with trimethylboroxine

A hydroxorhodium complex coordinated with a chiral diene ligand catalyzed the asymmetric addition of trimethylboroxine to N-sulfonylarylimines to give high yields of chiral 1-aryl-1-ethylamines with high enantioselectivity.     

Polymerization of Styrene Initiated by Photoexcited Charge-Transfer Complex

Photopolymerization of styrene in the presence of pyromellitic dianhydride, an electron acceptor which forms a charge-transfer complex with the monomer, was studied. Polymerization was initiated by illumination with a light of wavelength longer than 350 nm, where only the charge-transfer absorption band exists. It was found that the reaction involves cationic and radical polymerizations and that the reaction course strongly depends on polarity of the system. It was also suggested by the dependence of the rate of polymerization on light intensity and temperature that the cationic polymerization consists of free ion and ion-pair polymerizations. These results were compared with those of the photoinduced cationic polymerization of α-methylstyrene, which has previously been studied.     

PUMMERER-TYPE REACTION OF SULFILIMINES WITH ACETIC ANHYDRIDE

Abstract

Methyl phenyl N-p-tosylsulfilimine was found to undergo Pummerer type rearrangement affording α-acetoxymethyl phenyl sulfide similar to the corresponding sulfoxide. In order to clarify the mechanism of the reaction of methyl p-substituted phenyl sulfilimines with acetic anhydride, kinetic experiments were carried out. A large negative value of activation entropy, a relatively small value of activation enthalpy and the influence of acetic acid seem to reveal that the initial intermediate, i.e., acetylated sulfilimine, receives the nucleophilic attack of acetate ion to replace imino group, and this substitution reaction is the rate determining step.     

Thermomechanical analysis of a polymer dispersed liquid crystal containing a thermoplastic elastomer

Bulk samples of polymer dispersed liquid crystals (PDLCs) containing polystyrene (PS) and a thermoelastic elastomer as polymer matrices, have been prepared by a thermally-induced phase separation method. Thermomechanical analysis measurements revealed that the PDLC containing the thermoplastic elastomer possessed rubber-like elasticity even in the mesomorphic temperature range of the LC while the PDLC based on PS showed plastic deformation during the measurement.