Homogeneous manganese-catalyzed hydroamination of alkenes via the reductive coupling with nitroarenes

We report an efficient and operationally simple protocol for the manganese-catalyzed synthesis of secondary amines via the reductive coupling of nitroarenes and alkenes. Only commercially available reagents were required, and excellent to moderate results were achieved with styrenes, which have been identified as challenging substrates under this strategy. Moreover, both electron-donating and electron-withdrawing groups were relatively well accommodated for both coupling partners, and no second reductive treatment was necessary. Additional mechanistic studies revealed a homogeneous system, operating through a radical pathway, with a carbon-centered radical and a nitroso species (derived from alkene and nitro compound, respectively) as the key reactive species.

Automated summary

We developed a manganese-catalyzed method for the synthesis of secondary amines by reductively coupling nitroarenes and alkenes. The protocol showed high efficiency and simplicity, utilizing commercially available reagents. Styrenes, which are challenging substrates, achieved excellent to moderate yields under this strategy. Mechanistic studies revealed a homogeneous system operating through a radical pathway, with carbon-centered radical and nitroso species as key reactive intermediates.