Combined Photoredox/Enzymatic C−H Benzylic Hydroxylations

Chemical transformations that install heteroatoms into C?H bonds are of significant interest because they streamline the construction of value‐added small molecules. Direct C?H oxyfunctionalization, or the one step conversion of a C?H bond to a C?O bond, could be a highly enabling transformation due to the prevalence of the resulting enantioenriched alcohols in pharmaceuticals and natural products,. Here we report a single‐flask photoredox/enzymatic process for direct C?H hydroxylation that proceeds with broad reactivity, chemoselectivity and enantioselectivity. This unified strategy advances general photoredox and enzymatic catalysis synergy and enables chemoenzymatic processes for powerful and selective oxidative transformations.     

Supramolecular Recognition Allows Remote,Site‐Selective C−H Oxidation of Methylenic Sites in Linear Amines

Site‐selective C−H functionalization of aliphatic alkyl chains is a longstanding challenge in oxidation catalysis, given the comparable relative reactivity of the different methylenes. A supramolecular, bioinspired approach is described to address this challenge. A Mn complex able to catalyze C(sp³)‐H hydroxylation with H₂O₂ is equipped with 18‐benzocrown‐6 ether receptors that bind ammonium substrates via hydrogen bonding. Reversible pre‐association of protonated primary aliphatic amines with the crown ether selectively exposes remote positions (C8 and C9) to the oxidizing unit, resulting in a site‐selective oxidation. Remarkably, such control of selectivity retains its efficiency for a whole series of linear amines, overriding the intrinsic reactivity of C−H bonds, no matter the chain length.