ESR study of Mn2+ in GeTe and GeTeSi glasses

The electron spin resonance spectra of Mn²⁺ ions have been studied in Ge_xTe_100?x with x = 15, 17.5 and 20, and Ge_20?xTe₈₀Si_x with 0 ?x? 20. All samples are found to exhibit six hyperfine lines centered at g = 4.3 with hyperfine interaction constant A = 56 × 10^?4cm^?1. The g = 4.3 line is interpreted as being caused by Mn²⁺ ions incorporated in the amorphous network and surrounded by four Te atoms in an arrangement of orthorhombic symmetry. Some of the samples of GeTe show a g = 2.0 line. This line also appears after heat treatment in air at temperatures above the glass transition temperature. It is concluded that the g = 2.0 line is caused by Mn²⁺ ions in phase separated microcrystalline or concentrated regions of MnO in the glass.     

On Solutions of the q-Hypergeometric Equation with q N = 1

We consider the q-hypergeometric equation with q ^N = 1 and , , . We solve this equation on the space of functions given by a power series multiplied by a power of the logarithmic function. We prove that the subspace of solutions is two-dimensional over the field of quasi-constants. We get a basis for this space explicitly. In terms of this basis, we represent the q-hypergeometric function of the Barnes type constructed by Nishizawa and Ueno. Then we see that this function has logarithmic singularity at the origin. This is a difference between the q-hypergeometric functions with 0 < |q| < 1 and at |q| = 1.     

Nickel-catalyzed intermolecular coupling of 1,3-dienes and aldehydes via transmetalation of nickelacycles with diisobutylaluminum acetylacetonate

Intermolecular coupling reactions of 1,3-dienes and aldehydes via transmetalation of nickelacycle intermediate with (i)Bu(2)Al-acac were investigated. In the reactions, a linear adduct or a branched adduct was produced, depending upon the nature of 1,3-dienes and aldehydes, via two nickelacycles that were relatively stable among the four possible nickelacycles because of the equilibrium with pi-allynickel forms.     

Novel photodegradation of the antifungal antibiotic pyrrolnitrin in anhydrous and aqueous aprotic solvents

The UV irradiation of pyrrolnitrin (1a), which is an antibiotic clinically useful against dermatophytosis and possesses a unique 2-(pyrrol-3-yl)nitrobenzene moiety in the molecule, in an anhydrous aprotic solvent resulted in the exclusive formation of transient 7,4'-dichlorospiro[1,3-dihydrobenzo(c)isoxazole-3,3'-pyrrolin-2'-one] (2a) via the intramolecular oxidation of the juxtaposed pyrrole ring by the triplet-excited nitro group. The irradiation in an aqueous aprotic solvent, however, allowed the concurrent occurrence of intramolecular cyclization by the singlet-excited nitro group in 1a and the hydroxylation at the 2-position of the pyrrole ring by water to afford 3,7-dichloro-8-hydroxy-8,8a-dihydropyrrolo[2,3-b]indol-2-one (3a), accompanied by the formation of 2a. Elongation of the irradiation time in these photoreactions caused a rapid consumption of the products, 2a and 3a, to give undetermined polar polymeric products. The present results indicate that the photodegradation of 1a is significantly influenced by the presence of water in the reaction media and by the nature of its excited state. Thus, the loss of the antifungal activities by the photosensitive antibiotic 1a was chemically proved.     

First total synthesis of artepillin C established by o,o'-diprenylation of p-halophenols in water

We have demonstrated that prenylation of p-halophenols was dependent on the solvent effect and succeeded in o,o'-diprenylation of p-halophenols in water. Following the Mizoroki-Heck coupling of the diprenyl-p-iodophenol 3c with methyl acrylate and then hydrolysis, we first synthesized artepillin C [3-(4-hydroxy-3,5-di(3-methyl-2-butenyl)phenyl)-2(E)-propenoic acid] (1), which is a biologically active constituent of propolis. These reactions may be applicable to the synthesis of various useful natural products such as 2,4,6-trisubstituted phenol derivatives.