Shining light on nitro group: distinct reactivity and selectivity

Abstract

Nitro moiety is an indispensable functional group in organic synthesis due to its facile introduction and reduction to the corresponding amines for a plethora of organic transformations. Owing to its distinct electronegative and convensional properties, it has been used for activated aromatic nucleophilic substitution (SNAr) reaction, Smiles reaction, Henry reaction, acyl anion equivalent, etc. Recently, excellent photochemical properties of nitroarenes have been rediscovered by several groups and exploited its untapped potential in organic synthesis under UV or visible light irradiation. The photoexcited nitroarenes perform facile reduction to amines, azo-coupling, metal-free, reductive C-N coupling with boronic acids via 1,2-boronate shift, hydrogen atom transfer (HAT) properties, oxygen atom transfer for anaerobic oxidation of organic molecules, molecular editing via nitrene intermediate, denitrative coupling of β-nitrostyrene, radical a-alkylation of nitroalkanes etc. It is also used as a photolabile protecting group in medicinal chemistry and chemical biology applications. Here, we summarise these recent findings on the visible light-mediated transformations involving nitro-containing organic molecules.