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Determining the stereochemistry at the anomeric position of glycosides is imperative in chemical synthesis. As for 1,2-cis-β-glycosides such as β-mannosides, 13C-1H coupling constants, 1JCHs, are conventionally used when glycosides are in an ordinary chair conformation. In this work, we searched for appropriate criteria to determine the stereochemistry of products in a recently developed glycosylation reaction using 2,6-lactones. As a result, we found that α-glycosides exhibited vicinal coupling constants of around 3.0 Hz at the anomeric proton, as well as a long-range coupling between protons at C-1 and C-5, whereas β-glycosides had coupling constants of 1.2 Hz at most. These figures are expected to be useful for future assignments. In addition, the observations obtained from this study revealed the conformation of glycosides with a 2,6-lactone moiety.

In order to improve the solubility of intensively fluorescent 2,5-bis(benzimidazol-2-yl)pyrazine (BBIP), we synthesized new BBIP derivatives (2, 3a,b, and 5a,b) possessing two alkyl chains at the N-1 and N-1′ positions of the two benzimidazole moieties. Characterization of these compounds demonstrated that they exhibit high fluorescence intensity even in protic solvents, as well as solvatochromic fluorescence, in which their fluorescence maxima in aqueous methanol exhibited bathochromic shift with increasing ɛr value of the medium. We utilized 5a as a microenvironment polarity probe to indicate the variation in polarity around the backbone of the temperature-sensitive poly(N-isopropylacrylamide) by measuring the spectral change caused by the thermal phase transition of the polymer.

As a chemiluminescent chemosensor that emits yellow light on reacting with a superoxide radical anion (O 2 − ) and has a lipophilic character, a 6-phenylimidazo[1,2- a ]pyrazin-3(7 H )-one derivative possessing a boradiazaindacene (BODIPY) at the para position of 6-phenyl ( 1 ) was synthesized. The lipophilicity of 1 was investigated by reversed-phase liquid chromatography, and its log P ow value was found to be 3.57. This value was much higher than that of 2-methyl-6-(4-methoxypheyl)imidazo[1,2- a ]pyrazin-3(7 H )-one (MCLA, log P ow =1.19) and 6-[4-[2-{ N ′-(5-fluoresceinyl)thioureido}ethoxy]phenyl]-2-methylimidazo[1,2- a ]pyrazin-3(7 H )-one (FCLA, log P ow =−0.08), and it was comparable to that of benzenoid hydrocarbons. The O 2 − -induced chemiluminescence of 1 was investigated using the hypoxanthine/xanthine oxidase system as the source of O 2 − , and as a result, yellow emission was observed. The maximum wavelength was observed at 542 nm, and it was longer than that of FCLA.

Botryllazine B analogues of diverse substitution patterns have been prepared, and their in vitro inhibitory activities against recombinant human aldose reductase (h-ALR2) evaluated. Among the 15 compounds tested, 6-(4-aminophenyl)-2-(4-hydroxyphenyl)carbonylpyrazine ( 7b ) proved to be the most potent inhibitor, with IC 50 =0.91 μM. Kinetic analyses of 7b and botryllazine B ( 1 ) revealed that these inhibitors exhibit an unprecedented mixed-type inhibition on h-ALR2 with respect to the substrate d , l -glyceraldehyde, in the presence of NADPH at inhibitor concentrations near the IC 50 values.

The concise synthesis of (8aR)-(−)-albaconol (1) from (8aR)-albicanol (2) obtained from the lipase-assisted asymmetric acetylation of rac-2, was achieved in 45% overall yield (eight steps). By comparison of the sign of specific rotation of between synthetic (8aR)-(−)-albaconol (1) and natural (+)-albaconol (1), the absolute structure of natural (+)-1 was determined to be 1R,2R,4aS,8aS configuration.