Ruthenium-catalyzed acceptorless dehydrogenation of heterocycles

Highly efficient, selective ruthenium-catalyzed acceptorless dehydrogenation of heterocycles is reported. A simple and readily accessible dinuclear monohydrido bridged ruthenium complex [{( η 6 - p -cymene)RuCl} 2 ( μ -H- μ -Cl)] 1 is employed as a catalyst. The proposed reaction mechanism for dehydrogenation of N-heterocycles begins with N–H activation by the metal center; subsequent C–H activation and isomerization lead to the liberation of molecular hydrogen and formation of N-heteroarenes. Overall, this protocol can have applications in developing hydrogen storage strategies, biomass valorization, and atom-economical synthesis of heteroarenes. Graphical abstract A simple and readily accessible dinuclear monohydrido bridged ruthenium complex [{( η 6 - p -cymene)RuCl} 2 ( μ -H- μ -Cl)] is reported as a catalyst for acceptorless dehydrogenation of heterocycles. The proposed mechanism involves initial N–H activation of heterocycles by the metal center followed by isomerization, which provides the product N-heteroarenes with the liberation of molecular hydrogen.