Convenient Microscale Synthesis of a Coumarin Laser Dye Analog

The expeditious Knoevenagel synthesis of 3-acetyl-7-(diethylamino)-2H-1-benzopyran-2-one, a fluorescent coumarin laser dye analog, is described. This experiment is suitable for inclusion in mid-level undergraduate organic chemistry laboratories. The synthesis highlights the efficiency, safety, and time effectiveness of microscale chemistry while stressing fundamental reaction mechanisms and analytical techniques to students. The coumarin product affords informative proton NMR, infrared, UV–visible, and fluorescence spectra that introduce and reinforce essential concepts such as molecular light absorption and emission.