Synthesis of a Benzodiazepine-Derived Rhodium NHC Complex by C−H Bond Activation

The synthesis and characterization of a Rh(I)−NHC complex generated by C−H activation of a 1,4-benzodiazepine heterocycle are reported. This complex constitutes a rare example of a carbene tautomer of a 1,4-benzodiazepine aldimine stabilized by transition metal coordination and demonstrates the ability of the catalytically relevant RhCl(PCy3)2 fragment to induce NHC-forming tautomerization of heterocycles possessing a single carbene-stabilizing heteroatom. Implications for the synthesis of benzodiazepines and related pharmacophores via C−H functionalization are discussed.