Enantioselective catalytic β-amination through proton-coupled electron transfer followed by stereocontrolled radical-radical coupling.

Enantioselective catalytic β-amination through proton-coupled electron transfer followed by stereocontrolled radical–radical coupling† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c7sc02031g Click here for additional data file.

N-heterocyclic carbene-catalyzed radical reactions for highly enantioselective β-hydroxylation of enals.

An N-heterocyclic carbene-catalyzed β-hydroxylation of enals is developed. The reaction goes through a pathway involving multiple radical intermediates, as supported by experimental observations. This oxidative single-electron-transfer reaction allows for highly enantioselective access to β-hydroxyl esters that are widely found in natural products and bioactive molecules.

Enantioselective N-Heterocyclic Carbene-Catalyzed β-Hydroxylation of Enals Using Nitroarenes: An Atom Transfer Reaction That Proceeds via Single Electron Transfer

A novel oxidative N-heterocyclic carbene-catalyzed reaction pathway has been discovered. Alkyl and aryl enals undergo β-hydroxylation via oxygen atom transfer from electron-deficient nitrobenzenes, followed by trapping of the resultant acyl azolium by the solvent. The proposed mechanism involves a single electron transfer event to initiate the reaction followed by radical recombination. This re...

Function of the diiron cluster of Escherichia coli class Ia ribonucleotide reductase in proton-coupled electron transfer.

The class Ia ribonucleotide reductase (RNR) from Escherichia coli employs a free-radical mechanism, which involves bidirectional translocation of a radical equivalent or "hole" over a distance of ~35 Å from the stable diferric/tyrosyl-radical (Y122(•)) cofactor in the β subunit to cysteine 439 (C439) in the active site of the α subunit. This long-range, intersubunit electron transfer occurs by ...

N-heterocyclic carbene organocatalytic reductive β,β-coupling reactions of nitroalkenes via radical intermediates.

An unprecedented N-heterocyclic carbene catalytic reductive β,β-carbon coupling of α,β-nitroalkenes, by using an organic substrate to mimic the one-electron oxidation role of the pyruvate ferredoxin oxidoreductase (PFOR) in living systems, has been developed. The reaction goes through a radical anion intermediate generated under a catalytic redox process. For the first time, the presence of rad...