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 intermolecular C-H amination reaction. The developed system shows high catalytic activity without phosphorous based additives and delivers diverse carbazole derivatives in good to excellent yields. Further these N-aryl carbazoles get post functionalized at C1 selective position including nitration with AgNO3 (4a) and chalcogenation with disulfides and diselenides (5a). The molecular structure of Pd-MIC complex was confirmed by X-ray crystallography and also, we have performed several control experiments for the establishment of a plausible catalytic pathway.