Palladium-catalyzed one-pot Suzuki coupling followed by arylpalladium addition to aldehyde: a convenient route to fluoren-9-one derivatives

Various fluoren-9-one derivatives were prepared efficiently by a one-pot reaction involving sequential Suzuki coupling of 2-bromophenyl boronic acid with 2-bromocarboxaldehyde followed by intramolecular arylpalladium addition to aldehyde.     

Synthesis and Anticancer, Antiinflammatory,and Analgesic Activity Evaluation of Some Sulfa Drug and Acridine Derivatives

 Various sulfa drugs were condensed with 4-isothiocyanato-4-methyl-2-pentanone at pH∼3–5 by refluxing in methanol to give various substituted mercaptopyrimidines. On condensation with 9-chloro-2-substituted or -unsubstituted acridines, sulfathiazole gave the corresponding condensed products. N-Ethylaminoadenosine reacted with 9-chloroacridine to the coupled product. Condensation of sulfathiazole with 9-isothiocyanato-2,4-substituted or -unsubstituted acridines afforded the corresponding condensed compounds. The structures of all synthesized compounds were confirmed by spectroscopic methods. Anticancer, antiinflammatory, and analgesic activities of all compounds were investigated.     

Hybrid peptide design. Hydrogen bonded conformations in peptides containing the stereochemically constrained gamma-amino acid residue, gabapentin

The crystal structure of 12 peptides containing the conformationally constrained 1-(aminomethyl)cyclohexaneacetic acid, gabapentin (Gpn), are reported. In all the 39 Gpn residues conformationally characterized so far, the torsion angles about the Calpha-Cbeta and Cbeta-Cgamma bonds are restricted to the gauche conformation (+/-60 degrees ). The Gpn residue is constrained to adopt folded conformations resulting in the formation of intramolecularly hydrogen-bonded structures even in short peptides. The peptides Boc-Ac6c-Gpn-OMe 1 and Boc-Gpn-Aib-Gpn-Aib-OMe 2 provide examples of C7 conformation; peptides Boc-Gpn-Aib-OH 3, Boc-Ac6c-Gpn-OH 4, Boc-Val-Pro-Gpn-OH 5, Piv-Pro-Gpn-Val-OMe 6, and Boc-Gpn-Gpn-Leu-OMe 7 provide examples of C9 conformation; peptide Boc-Ala-Aib-Gpn-Aib-Ala-OMe 8 provides an example of C12 conformation and peptides Boc-betaLeu-Gpn-Val-OMe 9 and Boc-betaPhe-Gpn-Phe-OMe 10 provide examples of C13 conformation. Gpn peptides provide examples of backbone expanded mimetics for canonical alpha-peptide turns like the gamma (C7) and the beta (C10) turns. The hybrid betagamma sequences provide an example of a mimetic of the C13 alpha-turn formed by three contiguous alpha-amino acid residues. Two examples of folded tripeptide structures, Boc-Gpn-betaPhe-Leu-OMe 11 and Boc-Aib-Gpn-betaPhg-NHMe 12, lacking internal hydrogen bonds are also presented. An analysis of available Gpn residue conformations provides the basis for future design of folded hybrid peptides.     

An investigation of how perceptions of mathematics ability can affect elementary statistics performance

This study investigates the effects of perceived mathematics ability (PMA) on the learning process with special reference to 147 undergraduates following an elementary statistics (ES) course. A model incorporating PMA together with aptitude, effort put in, expected grade, motivation to do well and interest in the subject, which are deemed to be either directly or indirectly associated with performance, is developed. PMA itself is not a good predictor of ES performance, rather its effect may be channelled through interest, expected grade and motivation to do well in ES. Low perception in mathematics ability impedes effort put forth when learning ES. The influence of PMA on ES performance is likely to be the consequence of the belief that mathematics is essential to learn ES.     

Phase transition in Bi<Subscript>8</Subscript>Fe<Subscript>6</Subscript>Ti<Subscript>3</Subscript>O<Subscript>27</Subscript> multiferroic ceramics

The polycrystalline Bi₈Fe₆Ti₃O₂₇ compound was prepared by a high-temperature solid-state reaction technique. Preliminary structural analysis by X-ray diffraction (XRD) confirms the formation of a single-phase compound in an orthorhombic crystal system at room temperature. The elemental content of the compound was analyzed by EDAX microanalysis. Microstructural analysis by scanning electron microscopy (SEM) shows that the compound has well defined grains, which are distributed uniformly throughout the surface of the pellet sample. Detailed studies of temperature-dependent dielectric response at various frequencies show dielectric anomalies at 380, 389 and 403°C for 10 kHz, 100 kHz, and 1 MHz respectively. The hysteresis loop observed by applying an electric field of 12 kV/cm on the poled sample with smaller remanent polarization supports the existence of ferroelectricity in this material. The value of d₃₃ of the compound was found to be 19 pC/N.      

Electronic Transition Moment Variation in the C2Π–X2Σ+ System of Boron Monoxide

The extensive band system belonging to the C²Π_r–X²Σ⁺ transition of boron monoxide (BO) molecule lying in the vacuum ultraviolet region (150–230 nm) has been recorded in emission in a hollow cathode glow. A few new bands involving high v′ levels of C state have been observed. The Franck–Condon factors and r‐centroids were computed for the C–X system. By correlating the measured intensities to theory, the (relative) variation of the C–X electronic transition moment with internuclear separation was examined.