Photomediated reductive coupling of nitroarenes with aldehydes for amide synthesis

Abstract

In view of the widespread significance of amide functional groups in organic synthesis and pharmaceutical studies, an efficient and practical synthetic protocol that avoids the use of stoichiometric activating reagents or metallic reductants is highly desirable.

Anaerobic Hydroxylation of C(sp3)–H Bonds Enabled by the Synergistic Nature of Photoexcited Nitroarenes

“…The azoarene ( 13 ) and azoxyarene ( 14 ) byproducts were isolated from the reaction mixture of 2ag and characterized by NMR and HRMS (Scheme ). These byproducts, which form as the nitroarene is consumed and are present at the end of the reaction, are presumably generated via condensation of in situ-formed aniline and N -hydroxyaniline with the nitrosoarene. , Markedly, observation of these side products illustrates that fragmentation of the radical recombination product ( 12 ) leads to the desired C–H hydroxylation products ( 2 ) and the nitrosoarene byproduct.…”

Visible‐Light Photoredox Catalysis in the Late‐Stage Functionalization of Anticancer Agents

“…Wu and co‐workers [80] developed a direct photo‐mediated hydrogen atom transfer catalysed reductive amidation reaction with application of readily available aldehydes without use of metallic reductants and generation of toxic chemical waste. This method includes the reaction between nitrobenzene 61 and cyclopropanecarbaldehyde 62 in presence of 2 mol % TBADT, 2.5 equiv.…”

Visible light-mediated hydrogen atom transfer and proton transfer for the conversion of (2-vinylaryl)methanol derivatives to aryl aldehydes or aryl ketones

“…On the basis of visible light-mediated reaction modes of single electron transfer (SET) and energy transfer (EnT), various robust organic transformations can be achieved under mild conditions, such as C–H bond functionalizations, 3 C–C and C–X (X = heteroatom) bond formations as well as their selective cleavage and the subsequent downstream functionalizations and so on. 4 The SET pathway relies heavily on a redox process between a photosensitizer and a reaction substrate or a reaction intermediate, 5 so the excited-state photosensitizer often performs the role of an oxidant or a reductant. For example, in transition metal-catalyzed reductive coupling reactions, 6 the photoredox strategy is often used in place of a stoichiometric metal reductant, and hence the reaction can be performed under more environmentally-benign conditions.…”