Synthesis of mesoionic carbene-triazole-based Pd(ii) complex: promoting C–H activation toward N-aryl carbazoles

Abstract

Here, we report a triazolylidene-based mesoionic carbene (MIC) Pd(II) complex as an efficient catalyst for the synthesis of N-aryl carbazoles via an intermolecular C–H amination reaction. The developed system shows high catalytic activity without phosphorus-based additives and delivers diverse carbazole derivatives in good to excellent yields. Further, these N-aryl carbazoles can be post-functionalized at the C1 selective position, including nitration with AgNO₃ (4a) and chalcogenation with disulfides and diselenides (5a). The molecular structure of the Pd–MIC complex was confirmed by X-ray crystallography. Further, several control experiments were performed to support the proposed plausible catalytic pathway.