Transition Metal-catalyzed Construction Of N-containing Heterocyclic Compounds

Nitrogen containing molecules play an important role in the fields of medical and functional materials due to their unique chemical structures and properties. However, the reported procedures often suffered from many drawbacks, such as high cost, and low atom economy. Thus, the development of more efficient and sustainable methodologies for the construction of nitrogen containing heterocyclic compounds has been an important goal in synthetic organic chemistry. The present paper focuses on the transition metal-catalyzed reaction for the efficient and straightforward construction of nitrogen containing heterocyclic compounds. This paper contains three parts:(1) Iron-mediated synthesis of N-(2-hydroxyethyl) pyrrolesThis reaction realized the efficient synthesis of a series of N-2-hydroxyethyl) pyrroles catalyzed by FeCl2 in the presence of tert-butyl hydroperoxide as an oxidant, starting from ?-methylene ketones and diethanolamines. In this transformation, diarylethanone substrates, indanones,cyclic ketones and 1,3-dicarbonyl compounds all run smoothly, generating the corresponding pyrrole products in good to excellent yields. Thus, it provides a convenient pathway for the construction of N-(2-Hydroxyethyl) pyrroles.(2) Copper-mediated synthesis of 2,3-diaryl-2H-indazolesA copper-mediated annulation of 2-(1-substituted vinyl) anilines and aryl nitrosos was developed for the synthesis of 2,3-diaryl pyrazoles using DMSO as a solvent. No external reductant was required during the cyclization,where the vinyl served as a formal innate reductant. Moreover, compared with the traditional methods, no selectivity was involved. This method is an important supplement and development for the synthesis of indazoles.(3)Rh(?)-catalyzed bilateral cyclization toward acridinesA Rh(3)-catalyzed bilateral cyclization was developed for the efficient one pot synthesis of acridines via in situ formation and removal of imino as a transient directing group in the presence of catalytic amount of BnNH2. In this transformation, a sequential Rh(?)-catalyzed amination of C-H bond,cyclization and aromatization process was involved.