New N‐heterocyclic olefins (NHOs) are described with functionalization on the ligand heterocyclic backbone and terminal alkylidene positions. Various PdII–NHO complexes have been formed and their use as pre‐catalysts in Buchwald–Hartwig aminations was explored. The most active system for catalytic C−N bond formation between hindered arylamine and arylhalide substrates was accessed by combining a backbone methylated NHO with [Pd(cinnamyl)Cl]2 in the presence of NaOtBu as a base. In these active systems evidence suggests that catalysis is mediated by colloidal palladium metal, highlighting a different coordination ability of NHOs in comparison with commonly used N‐heterocyclic carbene co‐ligands.
Phosphine-scavenging Merrifield resins can significantly facilitate the synthesis of highly active Ru metathesis catalysts, including the second-generation Grubbs, Hoveyda, and indenylidene catalysts (GII, HII, InII).
Lab-based learning is an essential
part of any undergraduate chemistry
curriculum as it incorporates necessary and required hands-on experiential
learning. However, in response to the COVID-19 pandemic, many students
are learning from home, rendering laboratory instruction a particular
challenge. Options for educators include third party virtual and prerecorded
materials, at-home laboratory experiments, and original prerecorded
and real-time instruction. Here, we report the assessment of a variety
of technological setups for real-time and prerecorded original content
looking at a variety of audio and video sources as well as one-camera
and two-camera options. We intentionally selected equipment that we
had readily available and ensured our recordings were as close to
the student experience as possible by recording via a secondary computer
signed into an online learning platform. Upon a survey of a small
group of students at Quest University Canada, we found that 72% of
students preferred a two-camera setup using a smartphone to film the
instructor as a whole and a web camera to provide a close-up view
of the chemistry taking place. This setup was used for a diversity
of real-time and prerecorded experiments delivered remotely at Quest
University including titrations, basic synthetic reactions, and purifications.
For two of the experiments, a titration lab and a synthesis and purification
lab, we assessed the ability of different remote learning options
to meet pre-COVID-19 learning outcomes. Real-time, digital laboratory
instruction is clearly the most effective. In addition, we suggest
scenarios where using digital techniques may create efficiencies in
laboratory teaching upon the return to on-campus learning.
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