A selenium-catalysed para-amination of phenols.

Abstract

Antioxidant enzyme glutathione peroxidase (GPx) decomposes hydroperoxides by utilizing the different redox chemistry of the selenium and sulfur. Here, we report a Se-catalysed para-amination of phenols while, in contrast, the reactions with sulfur donors are stoichiometric. A catalytic amount of phenylselenyl bromide smoothly converts N-aryloxyacetamides to N-acetyl p-aminophenols. When the para position was substituted (for example, with tyrosine), the dearomatization 4,4-disubstituted cyclodienone products were obtained. A combination of experimental and computational studies was conducted and suggested the weaker Se-N bond plays a key role in the completion of the catalytic cycle. Our method extends the selenium-catalysed processes to the functionalisation of aromatic compounds. Finally, we demonstrated the mild nature of the para-amination reaction by generating an AIEgen 2-(2'-hydroxyphenyl)benzothiazole (HBT) product in a fluorogenic fashion in a PBS buffer.