Asymmetric reduction of prochiral inclusion complex in aqueous media

Abstract

In the formation of an inclusion compound, the interaction of both ionic and hydrogen bonds were shown to be involved in the asymmetric reduction of a keto acid in the presence of 6-deoxy-6-amino-β-cyclodextrin with NaBH₄ in an aqueous buffer solution. Furthermore, multiple interactions were elucidated and the enatioface differentiating reduction was induced in the concerted interactions. Asymmetric reduction of a keto acid in the presence of newly prepared alkylamino-substituted β-cyclodextrin (CD) gave a higher optical yield. There should be a steric effect by a substituent group on the CD to form the conformation favoured by the multi-interaction between host and guest A mechanistic scheme for the enatioface differentiating attack of a reducing reagent on the included substrate is suggested.     

Uncertainty relation on Wigner-Yanase-Dyson skew information

We give a trace inequality related to the uncertainty relation of Wigner-Yanase-Dyson skew information. This inequality corresponds to a generalization of the uncertainty relation derived by S. Luo (2005) [8] for the quantum uncertainty quantity excluding the classical mixture.     

Highly activatable and environment-insensitive optical highlighters for selective spatiotemporal imaging of target proteins

Optical highlighters are photoactivatable fluorescent molecules that exhibit pronounced changes in their spectral properties in response to irradiation with light of a specific wavelength and intensity. Here, we present a novel design strategy for a new class of caged BODIPY (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) fluorophores, based on the use of photoremovable protecting groups (PRPGs) with high reduction potentials that serve as both a photosensitive unit and a fluorescence quencher via photoinduced electron transfer (PeT). 2,6-Dinitrobenzyl (DNB)-caged BODIPY was efficiently photoactivated, with activation ratios exceeding 600-fold in aqueous solutions. We then combined this photoactivatable fluorophore with a SNAP (mutant of O(6)-alkylguanine DNA alkyltransferase) ligand to obtain a small-molecule-based optical highlighter for visualization of protein dynamics, using the well-established SNAP tag technology. As proof of concept, we demonstrate spatiotemporal imaging of the fusion protein of epidermal growth factor receptor (EGFR) with SNAP tag in living cells. We also demonstrate highlighting of cells of interest in live zebrafish embryos, using the fusion protein of histone 2A with SNAP tag.     

Experimental and theoretical analyses of azulene synthesis from tropones and active methylene compounds: reaction of 2-methoxytropone and malononitrile

A representative azulene formation from an active troponoid precursor (2-methoxytropone) and an active methylene compound (malononitrile) has been analyzed both experimentally and theoretically. (2)H-Tracer experiments using 2-methoxy[3,5,7-(2)H(3)]tropone (2-d(3)) and malononitrile anion give 2-amino-1,3-dicyano[4,6,8-(2)H(3)]azulene (1-d(3)) in quantitative yield. New and stable (2)H-incorporated reaction intermediates have been isolated, and main intermediates have been detected by careful low-temperature NMR measurements. The detection has been guided by mechanistic considerations and B3LYP/6-31(+)G(d) calculations. The facile and quantitative one-pot formation of azulene 1 has been found to consist of a number of consecutive elementary processes: (a) The troponoid substrate, 2-methoxytropone (2), is subject to a nucleophilic substitution by the attack of malononitrile anion (HC(CN)(2)(-)) to form a Meisenheimer-type complex 3, which is rapidly converted to 2-troponylmalononitrile anion (5). (b) The anion 5 is converted to an isolable intermediate, 2-imino-2H-cyclohepta[b]furan-3-carbonitrile (6), by the first ring closure in the reaction. (c) A nucleophilic addition of the second HC(CN)(2)(-) toward the imine 6 at the C-8a position produces the second Meisenheimer-type adduct 7. (d) The second ring closure leads to 1-carbamoyl-1,3-dicyano-2-imino-2,3-dihydroazulene (11). A base attacks the imine 11, which results in generation of a conjugate base 12 of the final product, azulene 1.     

Diastereoselective construction of azetidin-2-ones by electrochemical intramolecular C-C bond forming reaction

A convenient method for synthesis of optically active azetidin-2-ones using electrochemical oxidation has been exploited. The method consists of a diastereoselective intramolecular C-C bond forming reaction between active methylene and methyne groups through an electrochemical system in which positive iodine species acted as mediators under mild conditions.     

Hypoxia-sensitive fluorescent probes for in vivo real-time fluorescence imaging of acute ischemia

Based on the findings that the azo functional group has excellent properties as the hypoxia-sensor moiety, we developed hypoxia-sensitive near-infrared fluorescent probes in which a large fluorescence increase is triggered by the cleavage of an azo bond. The probes were used for fluorescence imaging of hypoxic cells and real-time monitoring of ischemia in the liver and kidney of live mice.     

Polar antiferromagnets produced with orbital order

Polar states are realized in pseudocubic manganite films fabricated on high-index substrates, in which a Jahn-Teller (JT) distortion remains an active variable. Several types of orbital orders (OOs) were found to develop large optical second harmonics, signaling broken-inversion symmetry distinct from their bulk forms and films on (100) substrates. The observed symmetry lifting and first-principles calculation both indicate that the modified JT q2 mode drives Mn-site off centering, which can be controlled by a magnetic-field-induced phase transition via a coupling of OO and spin orders.     

Design and synthesis of an enzyme activity-based labeling molecule with fluorescence spectral change

Methods of covalent labeling of a specific tag protein with small-molecular dyes play an important role in studying dynamic behaviors of proteins in living cells. On the basis of quinone methide chemistry, we designed and synthesized a beta-galactosidase labeling probe, CMFbeta-gal, which shows a fluorescence wavelength change accompanying the labeling reaction, owing to fluorescence resonance energy transfer (FRET). Since the FRET efficiency changes accompanying the labeling reaction, fluorescence of labeled protein can be observed separately from that of the unreacted probe, so immediate detection of the target protein is possible. This is the first report of a protein labeling probe which features a change of fluorescence wavelength upon reaction, allowing the labeled protein to be detected even in the presence of unreacted probe.     

Chain conformations of poly(gamma-benzyl-L-glutamate) pre and post an electrospinning process

In order to reveal mechanisms for the electrospinning of proteins, this study focuses on the polymer chain conformation, which is considered to be a critical factor for successful electrospinning. Poly(gamma-benzyl-L-glutamate) (PBLG) is employed and the relationships between the chain conformations of the pre-spun PBLG molecules and the morphologies of the post-spun PBLG fibers are investigated. By combining viscosity measurements, and circular dichroism and FT-IR spectroscopies, chain conformations of the pre- and post-spun PBLG are characterized. The chain conformations of the pre-spun PBLG changes from an alpha-helix to a random coil upon changing the solvent ratios of dichloromethane (CH(2)Cl(2)) and trifluoroacetic acid (CF(3)COOH) from 100:0 to 0:100. In an alpha-helix conformation, the morphology of PBLG fibers is relatively thick, while that of the random coil is thin and homogenous. The mean fiber diameters decrease when the chain conformations change from an alpha-helix to a random coil. FT-IR spectroscopy and wide-angle X-ray diffraction measurements reveal that electrospinning predominantly induces an alpha-helical conformation in post-spun PBLG fibers, and more highly crystallized fibers are generated as the alpha-helical content in the pre-spun solution increases.     

1,17‐Hepta­decane­diol

In the title compound, C₁₇H₃₆O₂, one of the hydroxyl groups has a gauche conformation with respect to the hydro­carbon skeleton, which is all‐trans, whereas the other has a trans conformation. The molecular shape is rod‐like and the compound has a rotator phase in which mol­ecules are assured greater motional freedom, as in liquid crystals. In addition, the mol­ecules arranged along the longest axis, b, form layers which are very similar to those of the smectic A liquid crystals.