Synthesis of Cyclopropyl Fluorescein Esters for Biochemical Assay

Fluorescent molecules have recently been used to observe and quantify biochemical processes. Within the last ten years, these molecules have been used to study serine hydrolases to learn more about how each one functions and what type of chemical groups they prefer. The data from the research on the BS2 serine hydrolase has revealed that there is a need to look further into the fluorogenic ester substrates that contain a cyclopropyl ring after data showed a strong preference to these substrates. This research project focused on the synthesis of fluorogenic cyclopropyl esters in preparation for biochemical assays. The synthesis was performed utilizing an original method developed by Dr. Luke Lavis. This original method needed to be altered for certain carboxylic acids, which revealed that extra steps to prevent hydrolysis of these unstable esters can lead to a larger yield, and success where past methods had failed. In total, thirteen syntheses were successfully completed, expanding the library of fluorescent molecules, and thus allowing further testing of the serine hydrolase preferences related to these substituted cyclopropyl ester derivatives. In the future, the modified methods used here could allow for further expansion of the library to include more unstable esters that have thus far been unattainable.