Palladium-Catalyzed Method for the Synthesis of Carbazoles via Tandem C−H Functionalization and C−N Bond Formation

Abstract

The development of a new method for the assembly of unsymmetrical carbazoles is reported. The strategy involves the selective intramolecular functionalization of an arene C-H bond and the formation of a new arene C-N bond. The substitution pattern of the carbazole product can be controlled by the design of the biaryl amide substrate, and the method is compatible with a variety of functional groups. The utility of the new protocol was demonstrated by the concise synthesis of three natural products from commercially available materials.

High‐Oxidation‐State Palladium Catalysis: New Reactivity for Organic Synthesis

“…This process is formally a palladium(IV)-based variant of the Buchwald-Hartwig C À N coupling. [30,31] Its synthetic usefulness was demonstrated by the preparation of an N-glycosyl carbazole (Scheme 7 a).…”

Palladium‐Catalyzed and Hybrid Acids‐Assisted Synthesis of [60]Fulleroazepines in One Pot under Mild Conditions: Annulation of N‐Sulfonyl‐2‐aminobiaryls with [60]Fullerene through Sequential C‐H Bond Activation, C‐C and C‐N Bond Formation

“…[6] We noticed that the utility of 2-aminobiaryls to construct different sizable heterocycles has also been developed; [7] for example, Miura et al reported the cross-coupling of Nsulfonyl-2-aminobiaryls with alkenes to afford phenanthridine derivatives [8] (six-membered rings). In 2005, Buchwald and co-workers demonstrated a highly efficient Pd(II)-catalyzed C À H bond activation/intramolecular amidation for the synthesis of carbazoles [9] (five-membered rings) from 2-acetaminobiphenyls. However, to the best of our knowledge, the use of N-protected-2-aminobiaryls to construct sevenmembered ring azepine compounds through Pd-catalyzed C À H bond activation has not been reported to date.…”

Transition Metal‐Catalyzed Formation of N‐Heterocycles via Aryl‐ or Vinyl C–H Bond Amination

“…Inspired by reports from Tremont [38] as well as Daugulis and coworkers, [39] Buchwald and co-workers reported that palladium(II) acetate catalyzed the formation of N-acetylcarbazoles 73 from 2-phenylanilides 72 (Scheme 18). [40] Optimization of the reaction conditions revealed that stoichiometric copper acetate or the combination of copper acetate and oxygen were required as oxidants. Using these conditions, a range of carbazoles could be accessed.…”