ABSTRACT
Photo-induced glycosylations of several acceptors with trichloroacetimidate donors using bis(2-naphthyl)disulfide as an organo-Lewis photoacid (LPA) catalyst proceeded effectively to give the corresponding glycosides in good to high yields. In addition, the ground and excited state absorption spectra of bis(2-naphthyl)disulfide with or without NEt3 suggested the Lewis acidity of bis(2-naphthyl)disulfide upon photo-irradiation.
ABSTRACT
The electron-doped SrTiO3 exhibits good thermoelectric properties, which makes this material a promising candidate of an n-type oxide thermoelectric device. Recent studies indicated that only a few percent co-doping of La and Mn in SrTiO3 substantially reduces the thermal conductivity, thereby greatly improving the thermoelectric figure of merit at room temperature. Our time-of-flight neutron scattering studies revealed that by doping both La and Mn into SrTiO3, the inelastic scattering spectrum shows a momentum-independent increase in the low-energy spectral weight approximately below 10 meV. The increase in the low-energy spectral weight exhibits a clear correlation with thermal conductivity. The correlation is attributed to dynamical and local structural fluctuations caused by the Jahn-Teller instability in Mn3+ ions coupled with the incipient ferroelectric nature of SrTiO3, as the origin of the low thermal conductivity.
ABSTRACT
Photoinduced glycosylation of alcohols with α-glucosyl trichloroacetimidates, using aryl urea and thioureas as organo photoacids, was examined under long wavelength UV (ultraviolet) irradiation. The results show, for the first time, that such glycosylations proceed effectively to give the corresponding glycosides in high yields. In addition, high ß-stereoselectivity was obtained under high concentration conditions, whereas high α-stereoselectivity was realized under low concentration conditions.
