Spectroscopic characterization of molecules is typically reinforced in the organic chemistry teaching laboratory via the analysis of reaction products by NMR and IR, and initial coverage of these topics can include experiments involving the identification of unknown compounds. To combine the unknown identification component with common laboratory techniques and relevant biologically active compounds, an experiment was developed allowing students to identify the active pharmaceutical ingredient present in various unknown tablets. The protocol involves pulverization of the unknown tablets, solid−liquid extraction, vacuum filtration, liquid−liquid extraction, and solubility tests prior to analysis via IR and NMR spectroscopy. Ultimately, this laboratory experiment provides a platform for students to reengage with many techniques covered in introductory organic chemistry laboratory experiments while gaining exposure and familiarity with spectroscopic methods.

Antibiotic resistance among bacteria puts immense strain on public health. The discovery of new antibiotics that work through unique mechanisms is one important pillar toward combating this threat of resistance. A functionalized amino dihydropyrimidine was reported to exhibit antibacterial activity via the inhibition of dihydrofolate reductase, an underexploited antibacterial target. Despite this promise, little is known about its structure–activity relationships (SAR) and mechanism of activity. Toward this goal, the aza-Biginelli reaction was optimized to allow for the preparation of focused libraries of functionalized amino dihydropyridines, which in some cases required the use of variable temperature NMR analysis for the conclusive assignment of compound identity and purity. Antibacterial activity was examined using microdilution assays, and compound interactions with dihydrofolate reductase were assessed using antimicrobial synergy studies alongside in vitro enzyme kinetics, differential scanning fluorimetry, and protein crystallography. Clear antibacterial SAR trends were unveiled (MIC values from >64 to 4 μg/mL), indicating that this compound class has promise for future development as an antibacterial agent. Despite this, the in vitro biochemical and biophysical studies performed alongside the synergy assays call the antibacterial mechanism into question, indicating that further studies will be required to fully evaluate the antibacterial potential of this compound class.