Preparation of C2-symmetric bicyclo[2.2.2]octa-2,5-diene ligands and their use for rhodium-catalyzed asymmetric 1,4-addition of arylboronic acids

[reaction: see text] C2-symmetric bicyclo[2.2.2]octa-2,5-dienes containing benzyl, phenyl, and substituted phenyl groups at 2 and 5 positions were prepared enantiomerically pure by way of bicyclo[2.2.2]octane-2,5-dione as a key intermediate. These chiral diene ligands were successfully applied to rhodium-catalyzed asymmetric 1,4-addition of arylboronic acids to alpha,beta-unsaturated ketones. High enantioselectivity (up to 99% ee) as well as high catalytic activity was observed in the addition to both cyclic and linear substrates.     

Significance of β-sheet formation for micellization and surface adsorption of surfactin

It was found that surfactin, an anionic lipopeptide biosurfactant, forms large rod-shaped micelles (micellar weight, 179 000, aggregation number n = 173) having a critical CMC of 9.4 × 10⁻⁶ M and a surface tension at the CMC γ_CMC of 30 mN m⁻¹ in 0.1 M NaHCO₃ (pH 8.7). This excellent surface-active behaviour was attributed to the ease of piling of surfactin molecules organized by β-sheet formation. Surfactin also showed a possible organization between molecules due to β-sheet structure at the air-water interface under forced experimental conditions.     

Decelerated chirality interconversion of an optically inactive 3(10)-helical peptide by metal chelation

A dynamically optically inactive 3(10)-helical peptide possessing metal chelating ability between the side-chains at the i and i + 3th residues was synthesized, and its metal complexes were shown to stabilize the peptide structure and the helical sense.     

Thermally stable and photoreactive polylactides by the terminal conjugation of bio-based caffeic acid

Caffeic acid terminally conjugated with polylactide showed high thermal stability and photoreactivity, and may be useful as a functional polylactide in the environmental and medical fields.     

Oxidative decarboxylative synthesis of 2-H-imidazolines from glyoxylic acid and 1,2-diamines

A novel method to prepare 2-H-imidazolines from glyoxylic acid monohydrate and 1,2-diamines is described; the key reaction of this method is the oxidative decarboxylation of the 2-carboxy imidazolidines by NBS.     

Ordinal classification using Comparative Molecular Field Analysis

Comparative Molecular Field Analysis (CoMFA) is most widely used as one of the 3-dimensional QSAR (3D-QSAR) methods to identify the relationship between chemical structure and biological activity. Conventional CoMFA requires at least 3 orders of experimental data, such as IC50 and Ki, to obtain a good model, although practically there are many screening assays where biological activity is measured only by a rating scale. Hence, rating classification-oriented CoMFA coupled with ordinal logistic regression has been developed, and its predictive ability and 3D graphical analysis ability have been investigated. As a result, this novel CoMFA (Logistic CoMFA) has been found to be more robust than conventional CoMFAs in both predictive and 3D graphical analysis abilities. Furthermore, Logistic CoMFA is useful since it can provide the probability of each rank.     

Local existence and blow-up criterion for the Euler equations in Besov spaces of weak type

We introduce Besov type function spaces, based on the weak L ^p -spaces instead of the standard L ^p -spaces, and prove a local-in-time unique existence and a blow-up criterion of solutions in those spaces for the Euler equations of perfect incompressible fluid in . For the proof, we establish the Beale-Kato-Majda type logarithmic inequality and commutator type estimates in our weak spaces. Abbreviate title: Euler equations in Besov spaces of weak type     

Diaminomethylenemalononitrile as a Chiral Single Hydrogen Bond Catalyst: Application to Enantioselective Conjugate Addition of α-Branched Aldehydes

An improved diaminomethylenemalononitrile organocatalyst, bearing a N,N-disubstituted structure, promoted enantioselective conjugate addition reaction of α-branched aldehydes with vinyl sulfone, affording adducts with excellent enantioselectivities (up to 96% ee). Mechanistic studies revealed that the diaminomethylenemalononitrile motif holds the vinyl sulfone substrate using a single hydrogen bond accompanied by multiple weak interactions, including electrostatic C−H⋅⋅⋅O interactions.     

Frustrated Lewis Pair Chelation as a Vehicle for Low‐Temperature Semiconductor Element and Polymer Deposition

The stabilization of silicon(II) and germanium(II) dihydrides by an intramolecular Frustrated Lewis Pair (FLP) ligand, PB , ⁱPr₂P(C₆H₄)BCy₂ (Cy=cyclohexyl) is reported. The resulting hydride complexes [PB{SiH₂}] and [PB{GeH₂}] are indefinitely stable at room temperature, yet can deposit films of silicon and germanium, respectively, upon mild thermolysis in solution. Hallmarks of this work include: 1) the ability to recycle the FLP phosphine‐borane ligand ( PB ) after element deposition, and 2) the single‐source precursor [PB{SiH₂}] deposits Si films at a record low temperature from solution (110 °C). The dialkylsilicon(II) adduct [PB{SiMe₂}] was also prepared, and shown to release poly(dimethylsilane) [SiMe₂]_n upon heating. Overall, this study introduces a “closed loop” deposition strategy for semiconductors that steers materials science away from the use of harsh reagents or high temperatures.