A5082087971- Oxidative Organic Chemistry Reactions
- Vanadium and Halogenation Chemistry
- Radical Photochemical Reactions
- Catalytic C–H Functionalization Methods
- Asymmetric Synthesis and Catalysis
- Chemical Synthesis and Reactions
- Fluorine in Organic Chemistry
- CO2 Reduction Techniques and Catalysts
- Metal-Catalyzed Oxygenation Mechanisms
- Asymmetric Hydrogenation and Catalysis
- Sulfur-Based Synthesis Techniques
- Chemical Synthesis and Analysis
- Enzyme Catalysis and Immobilization
- Chemical Reactions and Isotopes
- Porphyrin and Phthalocyanine Chemistry
- Cyclopropane Reaction Mechanisms
- Phytoestrogen effects and research
- Synthetic Organic Chemistry Methods
- Microbial Natural Products and Biosynthesis
- Signaling Pathways in Disease
- Carbohydrate Chemistry and Synthesis
- Chemical synthesis and alkaloids
- Intracranial Aneurysms: Treatment and Complications
- Polyoxometalates: Synthesis and Applications
- scientometrics and bibliometrics research
Emory University
2023-2025
Arizona State University
2020-2025
Princeton University
2018-2020
University of Rochester
2015-2018
Niagara University
2010-2014
Light teaches (co)enzymes new tricks is widely used in organic synthesis to excite electrons a substrate or catalyst, opening up reactive pathways desired product. Biology uses light sparingly this way, but coenzymes such as flavin can be driven excited states by light. Biegasiewicz et al. investigated reactivity and found suite of flavoenzymes that catalyze asymmetric radical cyclization when exposed “Ene”-reductases, reduced illuminated, converted starting materials containing an...
Intermolecular C–C bond-forming reactions are underdeveloped transformations in the field of biocatalysis. Here we report a photoenzymatic intermolecular hydroalkylation olefins catalyzed by flavin-dependent 'ene'-reductases. Radical initiation occurs via photoexcitation rare high-order enzyme-templated charge-transfer complex that forms between an alkene, α-chloroamide, and flavin hydroquinone. This unique mechanism ensures radical formation only when both substrates present within protein...
Flavin-dependent ene-reductases (EREDs) are known to stereoselectively reduce activated alkenes, but inactive toward carbonyls. Demonstrated here is that in the presence of photoredox catalysts, these enzymes will aromatic ketones. Mechanistic experiments suggest this reaction proceeds through ketyl radical formation, a pathway distinct from native hydride-transfer mechanism. Furthermore, reactivity accessible without modification either enzyme or cofactors, allowing both and non-natural...
Flavin-dependent 'ene'-reductases (EREDs) are highly selective catalysts for the asymmetric reduction of activated alkenes. This function is, however, limited to enones, enoates, and nitroalkenes using native hydride transfer mechanism. Here we demonstrate that EREDs can reduce vinyl pyridines when irradiated with visible light in presence a photoredox catalyst. Experimental evidence suggests reaction proceeds via radical mechanism where pyridine is reduced corresponding neutral benzylic...
Halooxindoles are versatile building blocks for the construction of complex oxindole-containing targets biological importance. Despite their synthetic value, catalytic methods to make 3-halooxindoles from readily available starting materials have remained undisclosed. We recently discovered that chloroperoxidase Curvularia inaequalis (CiVCPO) is a viable catalyst decarboxylative bromooxidation 3-carboxyindoles furnish 3-bromooxindoles with excellent regio- and chemoselectivity. In addition...
Further studies of the direct enantioselective α-hydroxymethylation aldehydes employing α,α-diarylprolinol trimethylsilyl ether class organocatalysts are described. This process has proven efficient for access to β-hydroxycarboxylic acids and δ-hydroxy-α,β-unsaturated esters from in generally good yields, excellent enantioselectivity, compatibility with a broad range functional groups aldehyde. The goal these was identify critical reaction variables that influence yield enantioselectivity...
The enzymatic synthesis of heterocycles is an emerging biotechnology for the sustainable construction societally important molecules. Herein, we describe enzyme-mediated strategy oxidative dimerization thioamides enabled by halide recycling vanadium-dependent haloperoxidase enzymes. This approach allows intermolecular biocatalytic bond formation using a catalytic quantity salt and hydrogen peroxide as terminal oxidant. established method applied to diverse range generate corresponding...
Abstract Flavin‐dependent ene‐reductases (EREDs) are known to stereoselectively reduce activated alkenes, but inactive toward carbonyls. Demonstrated here is that in the presence of photoredox catalysts, these enzymes will aromatic ketones. Mechanistic experiments suggest this reaction proceeds through ketyl radical formation, a pathway distinct from native hydride‐transfer mechanism. Furthermore, reactivity accessible without modification either enzyme or cofactors, allowing both and...
Thioketals are an important class of compounds that enable the selective preparation and protection carbonyl in chemical synthesis. Despite their synthetic utility, cleavage thioketals often requires use harsh conditions stoichiometric reagents largely bioincompatible. Herein, we describe a biocatalytic strategy for using enzymatic bromide recycling by vanadium-dependent haloperoxidase (VHPO) enzymes. This process involves thioketal through repetitive VHPO-mediated formation hypohalous acid...
Abstract Nitrogen‐containing compounds are valuable synthetic intermediates and targets in nearly every chemical industry. While methods for nitrogen‐carbon nitrogen‐heteroatom bond formation have primarily relied on nucleophilic nitrogen atom reactivity, molecules containing nitrogen‐halogen bonds allow electrophilic or radical reactivity modes at the center. Despite growing utility of bond‐containing compounds, selective catalytic strategies their synthesis largely underexplored. We...
Abstract Flavin‐dependent ‘ene’‐reductases (EREDs) are highly selective catalysts for the asymmetric reduction of activated alkenes. This function is, however, limited to enones, enoates, and nitroalkenes using native hydride transfer mechanism. Here we demonstrate that EREDs can reduce vinyl pyridines when irradiated with visible light in presence a photoredox catalyst. Experimental evidence suggests reaction proceeds via radical mechanism where pyridine is reduced corresponding neutral...
Halogenated heteroarenes are key building blocks across numerous chemical industries. Here, we report that vanadium haloperoxidases capable of producing 3-haloindoles through decarboxylative halogenation 3-carboxyindoles. This biocatalytic method is applicable to chlorination, bromination, and iodination in moderate high yields with excellent chemoselectivity.
Nitrogen-containing compounds are valuable synthetic intermediates and targets in nearly every chemical industry. While methods for nitrogen-carbon nitrogen-heteroatom bond formation have primarily relied on nucleophilic nitrogen atom reactivity, molecules containing nitrogen-halogen bonds allow reactivity through electrophilic or radical mechanisms at the center. Despite growing utility of nitrogen-halogen-containing compounds, selective catalytic strategies their synthesis largely...
Recently, a novel chiral cubane-based Schiff base ligand was reported to yield modest enantioselectivity in the Henry reaction. To further explore utility of this other asymmetric organic transformations, we evaluated its stereoselectivity cyclopropanation and Michael addition reactions. Although there no increase stereocontrol, upon computational evaluation using both M06L B3LYP calculations, it revealed that pseudo six-membered ring exists, through H-bonding cubyl hydrogen copper core....
A scalable synthesis of the potent antitumor agent, (−)-rasfonin, has been achieved. The synthetic strategy features a highly convergent approach based on single protocol construction both major fragments via catalytic enantioselective α-hydroxymethylation simple aliphatic aldehydes. route described successful in generation gram quantities natural product and serves as first to provide sufficient material continue studies related its mechanism action potential cancer therapeutic.
Halogenated heteroarenes are key building blocks across numerous chemical industries. Here, we report that vanadium haloperoxidases capable of producing 3-haloindoles through decarboxylative halogenation 3-carboxyindoles. This biocatalytic method is applicable to chlorination, bromination, and iodination in moderate high yields with excellent chemoselectivity.
Flavin-dependent ‘ene’-reductases (EREDs) are exquisite catalysts for effecting stereoselective reductions. While these reactions typically proceed through a hydride transfer mechanism, we recently found that EREDs can also catalyze reductive dehalogenations and cyclizations via single electron mechanisms. Here demonstrate enzymes redox-neutral radical to produce enantioenriched oxindoles from a-haloamides. This transformation is C–C bond forming reaction currently unknown in nature one...