Fluorescent Detection of Carbon−Carbon Bond Formation

Abstract

We have developed a new spectroscopic system for detecting carbon-carbon bond formation by fluorescence to enhance high-throughput catalyst screening and rapid characterization of catalysts on a small scale. Fluorogenic substrates composed of a fluorophore possessing an amino group are readily prepared as amides of alpha,beta-unsaturated carbonyl compounds and generally exhibit low fluorescence, while Michael or Diels-Alder reactions of these fluorogenic substrates provide products of significantly increased fluorescence. The product's fluorescence is approximately 20- to 100-fold higher than that of the substrate. The assay system was validated by screening potential catalysts of the Michael reaction and in solvent optimization experiments. The covalent combination of fluorophores possessing an amino group with alpha,beta-unsaturated carbonyl compounds should provide a diverse range of fluorogenic substrates that may be used to rapidly screen catalysts and to optimize reaction conditions.

Photophysical Properties of Cinchona Organocatalysts in Organic Solvents

“…[19][20][21][22][23] In recent years, applications of fluorescence spectroscopy for catalyst screening and chemical reaction monitoring have been reported. [24][25][26][27] These applications are based on the change of the fluorescence parameters of the substrate and the product of the catalytic reaction. For example, a method to screen for transition metalcatalyzed reactions based on fluorescence resonance energy transfer (FRET) and the use of this assay to identify catalysts for room-temperature Heck reactions of aryl bromides has been reported.…”

Enzyme assays for high-throughput screening

“…A pH indicator was used recently to detect haloalkane dehalogenase activity [40], based on the fact that the reaction produces hydrochloric acid and hence a drop in pH, which can be detected when the medium is carefully buffered. Fluorogenic maleimides known for their ability to reveal free thiol groups have been used to assay carbon-carbon bond formation by aldolase biocatalysts [41]. The method is very versatile and could also be exploited for measuring Diels-Alder reactions in the context of catalytic antibodies.…”

A Fluorogenic Aldehyde Bearing a 1,2,3-Triazole Moiety for Monitoring the Progress of Aldol Reactions

“…Fluorogenic substrates have also been employed in assessment of the catalytic activities of catalysts under different conditions and in screening of catalysts useful for synthetic organic chemistry 4. Detection of formation of fluorescent products from non-fluorescent fluorogenic substrates (i.e., detection of an increase in fluorescence) is typically more sensitive than detection of formation of non-fluorescent products from highly fluorescent reactants/substrates (i.e., detection of a decrease in fluorescence) 2. Here we report the development of a new type of fluorogenic aldehyde useful for monitoring the progress of aldol reactions through an increase in fluorescence.…”

“…Fluorogenic substrates that afford fluorescent products can be used for monitoring the progress of chemical reactions by fluorescence growth and are useful for high-throughput screening and rapid characterization of catalysts 1,2,3. Assay systems using fluorogenic substrates are critical for measurements and ranking of catalytic activities in the creation of designer enzymes and in directed enzyme evolution in vitro 3.…”

“…The aldol reaction is an important C-C bond forming reaction in enzyme catalysis and synthetic organic chemistry 2b,3,4,5. The development of efficient aldol catalysts is the topic of a number of current research efforts 3,4,5.…”