A Study of Highly Qualified Science Teachers' Career Trajectory in the Deep,Rural South: Examining a Link Between Deprofessionalization and Teacher Dissatisfaction

Science teacher retention, attrition, and migration continue to perplex educational scholars, political entities, as well as the general public. This study utilized an interpretive methodological design to generate assertions regarding career choice made by highly qualified science teachers in the deep, rural South through analysis of documents, interviews, focus groups, and observation. Generally considered “difficult to staff” because of location, socioeconomics, and demographics, Wilson County High School is an exemplar in science teacher retention and student achievement. Findings presented include how the science department at Wilson County improved student learning outcomes as well as the reasons why two of the highly qualified science teachers at this school were considering leaving the profession they love.     

Enantioselective Synthesis of Chiral Carboxylic Acids from Alkynes and Formic Acid by Nickel-Catalyzed Cascade Reactions: Facile Synthesis of Profens

We report a stereoselective conversion of terminal alkynes to α-chiral carboxylic acids using a nickel-catalyzed domino hydrocarboxylation-transfer hydrogenation reaction. A simple nickel/BenzP* catalyst displayed high activity in both steps of regioselective hydrocarboxylation of alkynes and subsequent asymmetric transfer hydrogenation. The reaction was successfully applied in enantioselective preparation of three nonsteroidal anti-inflammatory profens (>90 % ees) and the chiral fragment of AZD2716.     

Competition Between the Two σ-Holes in the Formation of a Chalcogen Bond

A chalcogen atom Y contains two separate σ-holes when in a R₁YR₂ molecular bonding pattern. Quantum chemical calculations consider competition between these two σ-holes to engage in a chalcogen bond (ChB) with a NH₃ base. R groups considered include F, Br, I, and tert-butyl (tBu). Also examined is the situation where the Y lies within a chalcogenazole ring, where its neighbors are C and N. Both electron-withdrawing substituents R₁ and R₂ act cooperatively to deepen the two σ-holes, but the deeper of the two holes consistently lies opposite to the more electron-withdrawing group, and is also favored to form a stronger ChB. The formation of two simultaneous ChBs in a triad requires the Y atom to act as double electron acceptor, and so anti-cooperativity weakens each bond relative to the simple dyad. This effect is such that some of the shallower σ-holes are unable to form a ChB at all when a base occupies the other site.     

Architectural control of polystyrene physical properties using branched anionic polymerization initiated at ambient temperature

Ambient temperature-initiated anionic polymerization has generated branched polystyrenes of varying molecular weights and architectures by inclusion of a distyryl branching comonomer into a conventional sec-Butylithium-initiated polymerization of styrene. Primary chain length control within the branched polymers, and restriction of the branching points to varying segments of the primary chains, led to variations of glass transition temperature with no direct correlation to the branched polymer molecular weight but a strong relationship to the length of individual chains comprising the branched macromolecules.     

Asymmetric Three‐Component Heck Arylation/Amination of Nonconjugated Cyclodienes

Substituted cyclohexylamines are becoming increasingly important in drug discovery. Asymmetric Heck insertion/amination of nonconjugated cyclodienes proceeds to give 5‐aryl cyclohexenylamines with good enantioselectivity and exclusive trans configurations. Primary and secondary anilines, indoline, and benzylamines are suitable amines. The weakly donating diphosphite Kelliphite forms a deep unsymmetrical pocket, which is essential for stereoselective anti attack of amines.     

Synthesis,crystal structure and conformational analysis of an unexpected [1,5]dithiocine product of aminopyridine and thiovanillin

The condensation reaction of 2‐mercapto‐3‐methoxybenzaldehyde with 3‐aminopyridine afforded an unexpected N‐alkylated [1,5]dithiocine instead of the N‐salicylideneaniline. The proposed mechanism for this condensation involves a strong intramolecular hydrogen bond between the thiol and the amine groups, leading to a second condensation. The corresponding product, i.e. 4,10‐dimethoxy‐13‐(pyridin‐3‐yl)‐6H,12H‐6,12‐epiminodibenzo[b,f][1,5]dithiocine methanol 0.463‐solvate, C₂₁H₁₈N₂O₂S₂·0.463CH₃OH, was characterized by single‐crystal X‐ray diffraction analysis. The supramolecular structure shows π–π stacking and S…S interactions in the crystal packing. Within the asymmetric unit, two geometries of the N atom are observed. Although a planar geometry should be expected, a pyramidal one is observed due to the crystal packing. The presence of the two geometries was further supported by density functional theory (DFT) calculations that show an electronic energy difference of less than 2 kJ mol^?1 between the two conformers.     

Asymmetric Wacker-Type Oxyallenylation and Azaallenylation of Cyclic Alkenes

Palladium-catalyzed three-component carboetherification of cyclic alkenes proceeded to give trans adducts exclusively with excellent enantioselectivity through a Wacker-type pathway. The reaction is also applicable to other oxygen nucleophiles, such as water, phenols, and carboxylic acids, as well as some electron-poor aryl amines.