Flavin-dependent proteins are dynamic catalysts for a variety of redox transformations in natural biosynthetic pathways. When investigated outside of an enzyme binding site, small molecule flavin mimics are well-described organocatalysts for electrophilic or nucleophilic oxidation reactions. In an effort to develop aerobic oxidation methods for chemical synthesis, flavin catalyst activation of molecular oxygen was investigated in new reaction systems. This study describes two uses of flavin catalysts driven by O2. Flavin catalysts efficiently generated H2O2 in polar solvents by reduction of molecular oxygen. Various stoichiometric reducing agents were investigated for catalyst turnover, including mimics of natural nicotinamide conenzymes that reduce flavin coenzymes in nature. Aerobic flavin systems catalyzed asymmetric epoxidations of electron-poor alkenes in the presence of chiral co-catalysts with excellent enantioselectivity and diastereoselectivity. Using a similar strategy, flavin catalysts efficiently perform one pot, multi-component, oxidative aromatizations of various heterocycles under mild, metal-free conditions. Rational catalyst and system design, recent substrate scope investigations, and extended reaction compatibility of these aerobic organocatalytic systems will be described.

Bioinspired aerobic organocatalysis: One pot preparation of aromatic heterocycles and in situ generation of H<sub>2</sub>O<sub>2</sub> for asymmetric epoxidations

246th National Meeting (2013)

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Bioinspired aerobic organocatalysis: One pot preparation of aromatic heterocycles and in situ generation of H2O2 for asymmetric epoxidations

Bioinspired aerobic organocatalysis: One pot preparation of aromatic heterocycles and in situ generation of H₂O₂ for asymmetric epoxidations