Furopyridines. XXV. Synthesis of 5-substituted furo [2,3-b]pyridines

Derivatives ( 2–8 ) of furo[2,3-b]pyridine having a substituent at the β-position to the ring nitrogen were prepared from the 5-nitro compound 1 via the Sandmeyer reaction.     

Solvent effects on the local structure of p-nitroaniline in supercritical water and supercritical alcohols

Raman spectra of p-nitroaniline in supercritical water and supercritical alcohols were measured, and the effects of solvents on the NO 2 and NH 2 stretching modes were investigated. The intensity and frequency of the NO 2 stretching mode significantly changed as a function of the solvent density and temperature. The frequency of the NO 2 stretching mode correlated with the absorption peak energy of the S 1<--S 0 transition. On the other hand, the vibrational frequency of the NH 2 stretching mode did not correlate with the absorption peak shift, although it had a large frequency shift as a function of the density. The correlation between the NO 2 frequency and absorption peak energy suggested that the solvent effects of supercritical water and supercritical alcohols were similar to those for nonpolar solvents. The density functional calculation using the polarizable continuum model and p-nitroaniline-water clusters qualitatively reproduced the density dependence of the NO 2 stretching mode as well as the solvent polarity dependence. Detailed vibrational analysis revealed that the coupling between the NO 2 and C-NH 2 vibrational motions at the harmonic level has an important effect on the intensity and frequency shift of the NO 2 stretching mode. The frequency shift of the NH 2 stretching mode correlated with the degree of hydrogen bonding between the solvent molecules estimated from NMR measurements [Hoffmann M. M.; Conradi, M. S. J. Phys. Chem. B. 1998, 102, 263]. The existence of intermolecular hydrogen bonding around the NH 2 group was demonstrated even at low-density conditions.     

Constituents of Crinoidea. 5. Isolation and structure of a new glycosyl inositolphosphoceramide-type ganglioside from the feather star Comanthina schlegeli

A new glycosyl inositolphosphoceramide-type ganglioside, CSP2, was obtained from the polar lipid fraction of the chloroform/methanol extract of the feather star Comanthina schlegeli together with a known same type of ganglioside CJP2. The structure of this ganglioside has been determined on the basis of chemical and spectroscopic evidence to be 9-O-methyl-(N-acetyl-alpha-D-neuraminosyl)-(2-->3)-inositolphosphoceramide, which contains C(16)-sphingosine and C(22:0)-, C(24:0)-fatty acid as major component. This is the first report on the isolation and structural elucidation of a glycosyl inositolphosphoceramide-type ganglioside possessing N-acetyl-neuraminic acid (NeuAc) residue.     

Raman spectroscopic study on the solvation of N,N-dimethyl-p-nitroaniline in room-temperature ionic liquids

Electronic absorption spectra and Raman spectra of N,N-dimethyl-p-nitroaniline (DMPNA) have been measured in various fluids from the gaseous-like conditions in supercritical fluids (SCFs) to highly polar room-temperature ionic liquids (RTILs). We found that the S0-S1 absorption band center of DMPNA in RTILs is mostly determined by the molar concentrations of ions. On the other hand, the bandwidth of the absorption spectrum does not follow the expectation from a simple dielectric continuum model. Especially in SCFs, the bandwidth of the absorption spectrum decreases with increasing solvent density, suggesting that the intramolecular reorganization energy is a decreasing function of the solvent density. The Raman shift of the NO2 stretching mode has been proven to be a good indicator of the solvent polarity; i.e., the vibrational frequency of the NO2 stretching mode changes from 1340 cm-1 in mostly nonpolar solvent such as ethane to 1300 cm-1 in water. The linear relationship between the absorption band center and the vibrational frequency of the NO2 mode, which was observed for conventional liquids in a previous paper (Fujisawa, T.; Terazima, M.; Kimura, Y. J. Chem. Phys. 2006, 124, 184503), holds almost well for all fluids including SCFs and RTILs. On the other hand, the vibrational bandwidth does not show a simple relationship with the absorption band center. The vibrational bandwidths in RTILs are generally larger in comparison with those in conventional liquids with similar polarity scales. Among the RTILs we investigated, the vibrational bandwidth loosely correlates with the molecular size of the anion. A similar dependence on the anion size is also observed for the bandwidth of the absorption spectrum. We have also investigated the excitation wavelength dependence of the Raman shift of the NO2 stretching mode in RTILs. The extent of the dependence on the excitation wavelength in all fluids is well correlated with the vibrational bandwidth.     

Protein diffusion probed by the transient grating method with a new type of photochromic molecule

A new type of photochromic molecule that can be used for diffusion coefficient (D) measurements of various proteins in solution is described. The absorption spectrum of this molecule is changed upon photoexcitation by the trans-cis isomerization reaction. Target proteins were labeled by this photochromic molecule in the dark and the translational motion of the proteins was detected by the transient grating (TG) method. The TG signal was simple enough to determine D accurately and was stable even for long-time irradiation by the laser light. The TG method using this probe molecule improves many drawbacks of the other techniques.     

Furopyridines. XXVI. Reactions of cyanopyridine derivatives of furo[2,3‐b]‐, ‐[3,2‐b]‐, ‐[2,3‐c]‐ and ‐[3,2‐c]pyridine

Bromination of α‐cyanopyridine derivatives of furopyridines 1a‐d gave the 2,3‐dibromo‐2,3‐dihydro compounds 2a‐d in excellent yields. Treatment of 2a‐d with sodium hydroxide in methanol yielded compounds formed through the dehydrobromination and solvolysis of the nitrile. N‐Oxidation of 1a and 1b gave N‐oxide in much poor yield, while 1c and 1d gave the N‐oxide 13c and 13d in good yields. The nucleophilic reactions (cyanation, chlorination and acetoxylatoin) of 13c through a Reissert‐Henze type reaction gave poor results, which would be caused by the strong electron withdrawing effect of the cyano group.     

Nonmechanical Optical Manipulation of Microparticle Using Spatial Light Modulator

A spatial light modulator (SLM) is introduced to an optical manipulation system. The real-time reconfigurable feature of the SLM makes it possible to perform an optical manipulation of microparticles without mechanical movements of optical parts. A liquid crystal SLM incorporated in the system forms a Fresnel zone plate (FZP). The beam spot generated by the FZP is imaged on a sample solution by reduction optics. A microparticle in the sample solution is trapped by the beam and manipulated by changing the addressing position of the FZP onto the SLM from a computer. The nonmechanical optical manipulation of microparticles is demonstrated for the first time.     

超流氦中的沸腾实验研究及其光学测量

在超流氦的沸腾实验中,随着静压液柱的降低,会出现不同的沸腾状态。在噪块沸腾中,一个与平板加热器大小相当的包在其表面上反复地长大、缩小,并伴随着巨大的噪声和剧烈的机械振动;在无噪声沸胶中,在平板加热器表面形成一个极稳定的气膜,并且,没有噪声和机械振动出现;而在两者之间,存在一个过渡的沸腾状态。在本文中,通过对沸腾过程中的可视化测量和对沸腾时的压力振动的测量,对超流氦中的不同沸腾状态进行了研究。     

RET receptor signaling: Function in development,metabolic disease,and cancer

The RET proto-oncogene encodes a receptor tyrosine kinase whose alterations are responsible for various human cancers and developmental disorders, including thyroid cancer, non-small cell lung cancer, multiple endocrine neoplasia type 2, and Hirschsprung’s disease. RET receptors are physiologically activated by glial cell line-derived neurotrophic factor (GDNF) family ligands that bind to the coreceptor GDNF family receptor α (GFRα). Signaling via the GDNF/GFRα1/RET ternary complex plays crucial roles in the development of the enteric nervous system, kidneys, and urinary tract, as well as in the self-renewal of spermatogonial stem cells. In addition, another ligand, growth differentiation factor-15 (GDF15), has been shown to bind to GFRα-like and activate RET, regulating body weight. GDF15 is a stress response cytokine, and its elevated serum levels affect metabolism and anorexia-cachexia syndrome. Moreover, recent development of RET-specific kinase inhibitors contributed significantly to progress in the treatment of patients with RET-altered cancer. This review focuses on the broad roles of RET in development, metabolic diseases, and cancer.