Ruthenium-catalyzed divergent deaminative and denitrative C–N cleavages: facile access to quinoxalines

Abstract

Divergent deaminative and denitrative C–N cleavages and cascade transformations using amines and nitroalkanes have been developed under a highly effective and environmentally-friendly catalytic system (RuCl₃/TFE). This protocol provides a versatile toolbox for the construction of quinoxalines under redox-neutral and mild conditions. Specifically, Ru-catalyzed acceptorless dehydrogenation and hydrogen borrowing strategies have been successfully implemented in the activation of amines, which is distinct from the dehydrogenation of frequently used alcohol as a hydrogen donor, enabling the deaminative coupling of amines with 2-arylanilines and 2-nitroarylpyrroles in the absence of additives. Crucially, unprecedented Ru-catalyzed denitrative C–NO₂ cleavages have been realized, wherein nitroalkanes were explored as unconventional electrophilic C synthons to accomplish [5 + 1] annulation. This identified process features exceedingly simple, environmentally-friendly conditions, ease of operation, a broad substrate scope, and the capacity to synthesise antileishmanial agents and bipolar host materials for OLEDs.