Design and use of fluorogenic aldehydes for monitoring the progress of aldehyde transformations

We describe the first examples of fluorogenic aldehydes useful for monitoring many types of reactions including aldol reactions, allylations, and reductions. The fluorogenic aldehydes were constructed by covalent combination of a fluorophore and an aldehyde moiety via a linker. In the resulting single molecule, the aldehyde functioned as a quencher of the fluorophore's fluorescence. The reaction product, modified at the aldehyde functionality, no longer served as an effective quencher. The reaction products showed up to approximately 80-fold higher fluorescence than the aldehyde reactants.