The coronavirus 2019 (COVID-19) outbreak in March led Davidson College to move from face-to-face classes and laboratories to mostly synchronous Zoom meetings. Prior to COVID-19, the majority of our ...faculty and students had little experience with remote instruction. With only 5 days to develop a plan, we revisited our individual and department learning goals and worked collectively to help each other redesign and redeploy our courses. In this reflective piece, we provide examples of how each member of our department collaborated with our students to ensure a relatively smooth transition to remote teaching across our entire curriculum while maintaining inclusive excellence. Specific strategies for adapting class meetings, assignments, assessments, additional support, and labs are provided along with select examples. Common themes across the curriculum included increased flexibility, the desire to maintain community, and the need for additional academic, technical, and emotional support. We hope our reflections will be helpful to our chemistry colleagues as we move into the uncertainty of the fall semester.
2-Pyridylboronic esters were generated by cross-coupling 2-bromopyridines with bis(pinacolato)diboron in the presence of a base and palladium catalyst. The boronic esters reacted in situ with ...unreacted 2-bromopyridines to afford high yields of 2,2′-bipyridines as homocoupled products. Depending upon the reaction conditions, varying amounts of protodeboronated products were also observed. An attempted cross-coupling between two different 2-bromopyridines produced a nearly statistical mixture of homo- and cross-coupled products.
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A two-step, one-pot synthesis of rufinamide, an antiepileptic drug, has been developed. 2,6-Difluorobenzyl azide reacts with methyl 3-methoxyacrylate followed by methanolic ammonia to afford ...rufinamide in 89% yield. The new method generates less waste and uses reagents that are both less expensive and less toxic than other reported syntheses.
2,2′‐Bipyridyl‐type compounds may be prepared by Suzuki‐Miyaura coupling of a 2‐pyridylboronic ester with 2‐haloazines and ‐azoles. Ten examples are presented with yields of 47 to 84%. Both ...arylbromides and arylchlorides undergo the coupling, but the reaction is sensitive to ring substitution adjacent to the halogen.
Nonstabilized 2-azaallyl anions bearing heteroatom substituents R1CHNC(X)R2(−)Li(+), where R1 and R2 are hydrogen or alkyl groups and X = OMe, SPh, or NR2 were generated and found to undergo ...efficient 3 + 2 cycloadditions with alkenes to provide 1-pyrrolines after loss of LiX. The 2-azaallyl anions were generated by tin−lithium exchange on stannyl imidates, thioimidates, or amidines R1CH(SnBu3)NC(X)R2 with n-butyllithium. The initially formed 1-pyrrolines were found to be deprotonated under the reaction conditions to afford 1-metalloenamines, which could be quenched with alkyl halides, carbonyl compounds, or MeSSMe to provide further functionalized 1-pyrrolines. Cyclic methoxy-substituted 2-azaallyl anions were generated and were found to undergo cycloadditions with alkenes to afford bridged azabicyclic compounds (1-methoxy-7-azabicyclo2.2.1heptanes and 1-methoxy-8-azabicyclo3.2.1octanes). These are the first examples of cyclic nonstabilized 2-azaallyl anions.
A preliminary survey of strategies for the asymmetric cycloaddition of nonstabilized 2-azaallyllithiums with alkenes is reported. The chiral diamine (−)-sparteine exerted little, if any, absolute ...stereocontrol. The attachment of a chiral auxiliary to the anion was more successful, leading to the first example of an asymmetric cycloaddition of a 2-azaallyllithium (
24
to
25
, 98% e.e.).
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The difference between the calculated heats of formation of gauche and anti conformers of monosubstituted propanes was determined and used as a new steric parameter (AG60 value) in QSAR calculations. ...The dihedral angle of the gauche conformation was fixed at 60° during the calculation to force interaction of the gauche groups. AG60 values are a thermodynamically determined steric measure in contrast to the Taft steric parameter, which is based upon kinetic measurements of ester hydrolyses. In comparisons to published QSAR studies, AG60 values correlated steric effects and biological activities very similarly to the Taft parameter. The average of r2 values from five QSAR studies for the Taft parameter was 0.887, while AG60 values averaged 0.883. Direct comparison of the Taft parameter and AG60 values showed a poor correlation (r2=0.300), indicating the two parameters are fundamentally different methods of measuring steric bulk.
In this work the process of elastic hadron scattering is discussed. In particular, scattering amplitudes for the various Pomeron models are compared. In addition, differential elastic cross section ...as a function of the scattered proton transverse momentum for unpolarised and polarised protons is presented. Finally, an implementation of the elastic scattering amplitudes into the GenEx Monte Carlo generator is discussed.
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