Introducing Click and Bioorthogonal Chemistry to Undergraduates: Preparing Diazaborines in an “Artificial Cellular Environment” Using Cheap and Accessible Reagents

Click chemistry and bioorthogonal reactions have revolutionized chemical biology, offering powerful tools for selective molecular transformations in complex biological environments. Despite their widespread adoption in research, these concepts are rarely included in undergraduate laboratory curricula due to the cost, instability, or complexity of many commonly used reagents. In this work, we present a simple and rapid, yet visually engaging, laboratory experiment for second-year undergraduate students that introduces the principles of click and bioorthogonal chemistry through the formation of a diazaborine heterocycle between 2-formylphenylboronic acid and benzylhydrazine. The experiment is conducted in a phosphate-buffered saline (PBS) solution enriched with lysine, glucose, and glutathione, creating an artificial cellular environment, and requires only standard reagents and basic equipment. Students observe product formation via precipitation, calculate yields, and reflect on the implications of compatibility and selectivity in biological settings. Additionally, the learning outcomes were assessed through lab notebooks, in-class performance, and a postlab quiz. In summary, the proposed activity effectively introduces boron click chemistry in an accessible context and demonstrates the relevance of bioorthogonal reactions in modern chemical biology.