The construction and manipulation of amine-containing architectures is of importance to academic and industrial development and discovery programs. The photochemical single-electron reduction of imine derivatives to generate α-amino radical intermediates has emerged as a powerful umpolung strategy for opening up underexplored routes to such amine motifs. Furthermore, these radicals have been shown to engage in a wide variety of chemistry, including radical–radical coupling, addition to electrophiles, and reductive amination chemistry. The concept has also begun to see application to iminium ion intermediates and the extension to enantiocontrolled C–C bond formation. This Perspective covers recent efforts in this synthetic strategy to simple and complex amine structures alike.

Ar eagent-controlled stereodivergent carbocyclisation of aryl aldimine-derived, photocatalytically generated, aamino radicals possessing adjacent conjugated alkenes,affording either bicyclic or tetracyclic products,i sd escribed. Under net reductive conditions using commercial Hantzsche ster,t he a-amino radical species underwent as ingle stereoselective cyclisation to give trans-configured amino-indane structures in good yield, whereas using as ubstituted Hantzsch ester as am ilder reductant afforded cis-fused tetracyclic tetrahydroquinoline frameworks,r esulting from two consecutive radical cyclisations.J udicious choice of the reaction conditions allowed libraries of both single and dual cyclisation products to be synthesised with high selectivity,n otable predictability, and good-to-excellent yields.C omputational analysis employing DFT revealed the reaction pathway and mechanistic rationale behind this finely balanced yet readily controlled photocatalytic system.

Ar eagent-controlled stereodivergent carbocyclisation of aryl aldimine-derived, photocatalytically generated, aamino radicals possessing adjacent conjugated alkenes,affording either bicyclic or tetracyclic products,i sd escribed. Under net reductive conditions using commercial Hantzsche ster,t he a-amino radical species underwent as ingle stereoselective cyclisation to give trans-configured amino-indane structures in good yield, whereas using as ubstituted Hantzsch ester as am ilder reductant afforded cis-fused tetracyclic tetrahydroquinoline frameworks,r esulting from two consecutive radical cyclisations.J udicious choice of the reaction conditions allowed libraries of both single and dual cyclisation products to be synthesised with high selectivity,n otable predictability, and good-to-excellent yields.C omputational analysis employing DFT revealed the reaction pathway and mechanistic rationale behind this finely balanced yet readily controlled photocatalytic system.