Vanishing of self-extensions over symmetric algebras

We study self-extensions of modules over symmetric artin algebras. We show that non-projective modules with eventually vanishing self-extensions must lie in AR components of stable type Z_A∞$\mathbb{Z}{A}_{\infty }$. Moreover, the degree of the highest non-vanishing self-extension of these modules is determined by their quasilength. This has implications for the Auslander–Reiten Conjecture and the Extension Conjecture.     

Cyclic amino acid salts as catalysts for the asymmetric Michael reaction

Different chiral cyclic amino acid alkali metal and ammonium salts were used as catalysts for the asymmetric Michael addition of aldehydes to nitrostyrene. The reaction yield and stereoselectivity depend slightly on the salt cation. The highest yield of the reaction (up to 100%) was obtained with (S)-morpholine-3-carboxylic acid salts, which gave moderate to good enantioselectivities (up to 72% ee) and diastereoselectivities (dr up to 89:11) whereas the highest selectivity was obtained with proline sodium salt (ee 88%).     

The Generalized Auslander–Reiten Condition for the bounded derived category

We consider the bounded derived category D ^b (R mod) of a left Noetherian ring R. We give a version of the Generalized Auslander–Reiten Condition for D ^b (R mod) that is equivalent to the classical statement for the module category and is preserved under derived equivalences.     

Flexural Properties of Glass Fibre Reinforced Composite with Partially Biodegradable Polymer Matrix

Summary: The aim of this study was to evaluate flexural properties of a partially biodegradable glass fibre reinforced composite after water immersion and dehydration. In addition water sorption and solubility was determined. E-glass fibres were preimpregnated with a biodegradable biopolymer of poly(hydroxyproline) amide (PA). The preimpregnated fibres were then further-impregnated with Bis-GMA–TEGDMA-resin and light polymerized (n = 6). There was also specimen made of plain polymer and FRC without PA. After water immersion and/or dehydration, the specimens were tested by the three-point bending test. The flexural strength and Young's modulus was increased in most cases after water immersion and dehydration except for PA containing specimens. The water sorption was <50 µg/mm³ for all studied specimens and solubility was 20 µg/mm³ for specimens without PA and 35 µg/mm³ for specimens with PA.     

Bimorpholine-mediated enantioselective intramolecular and intermolecular aldol condensation

Monosalts of N-substituted bimorpholine derivatives are efficient organocatalysts in intramolecular and intermolecular aldol reactions. The properties of the catalysts can be tuned either by the selection of an appropriate acid for the salt formation or by the change of a substituent at the nitrogen atom. In aldol condensation, i-Pr-substituted bimorpholine is the most stereoselective catalyst affording products in high yield with enantioselectivities up to 95% ee.     

3,3'-bimorpholine derivatives as a new class of organocatalysts for asymmetric Michael addition

New N-alkyl-3,3'-bimorpholine derivatives (iPBM) were revealed to be efficient organocatalysts for the asymmetric direct Michael addition of aldehydes to nitroolefins and a vinyl sulfone. In these transformations using iPBM, 1,4-adducts were afforded in high yields, with good to high levels of diastereo- and enantioselectivity. The stereochemical outcome of the reaction could be explained by an acyclic synclinal model. [reaction: see text]     

Directed Remote Lateral Metalation: Highly Substituted 2‐Naphthols and BINOLs by In Situ Generation of a Directing Group

A general synthesis of highly substituted 2‐naphthols based on a new carbanionic reaction sequence is demonstrated. The reaction exploits the dual nature of lithium bases consisting of consecutive ring opening of readily available coumarins with either LiNEt₂ or LiNiPr₂ into Z‐cinnamamides, thus generating a directing group in situ and allowing, by conformational freedom, a lateral directed remote metalation for ring closure to give the aryl 2‐naphthols in good to excellent yields. These transformations can be combined to provide a more efficient one‐pot process. Mechanistic insight into the remote lateral metalation step, demonstrating the requirement of Z‐cinnamamide, is described. Application of this methodology to the synthesis of highly substituted 3,3′‐diaryl BINOL ligands is also reported.