Synthesis of Carbazoles and Related Heterocycles from Sulfilimines by Intramolecular C−H Aminations

Abstract

While direct nitrene insertions into C−H bonds have become an important tool for building C−N bonds in modern organic chemistry, the generation of nitrene intermediates always requires transition metals, high temperatures, ultraviolet or laser light. We report a mild synthesis of carbazoles and related building blocks through a visible light‐induced intramolecular C−H amination reaction. A striking advantage of this new method is the use of more reactive aryl sulfilimines instead of the corresponding hazardous azides. Different catalysts and divergent light sources were tested. The reaction scope is broad and the product yield is generally high. An efficient gram‐scale synthesis of Clausine C demonstrates the applicability and scalability of this new method.

Antimicrobial Chlorinated Carbazole Alkaloids from the Sponge‐Associated Actinomycete Streptomyces diacarniLHW51701

“…Carbazole scaffolds, whether obtained from natural sources or by chemosynthesis, have gained considerable interest due to their broad range of biological activities such as antibacterial, neuroprotective, anti‐inflammatory, anticancer, and neuroinflammation diagnosis ligand properties. [ 1‐4 ] In recent years, increasing molecules of novel carbon skeletons with interesting bioactivities have been discovered from the symbiotic actinomycetes isolated from marine sponge, which are hitherto less‐explored compared to terrestrial microorganisms. [ 5 ] During the antimicrobial activities screening on the secondary metabolites of sponge‐associated Streptomyces diacarni LHW51701, [ 6 ] strong antimicrobial activities correlated with some prominent peaks with unique ultraviolet absorption and mass spectrometry attracted our interest for further exploring.…”

A combined experimental and theoretical study on the reactivity of nitrenes and nitrene radical anions

“…One concept harnesses the use of metal-catalyzed nitrene transfer reactions under UV light photochemical conditions to facilitate the formation of metal-nitrene intermediates (Fig. 1b ) 24 – 28 . Another concept employs highly specialized, tailor-made nitrene transfer reagents ( 7 ), relying on strong UV-light for their photolysis 29 .…”

Scalable Electrochemical Transition‐Metal‐Free Dehydrogenative Cross‐Coupling Amination Enabled Alkaloid Clausines Synthesis

“…Despite these meaningful advances, the approaches described above have disadvantages associated with the requirements of costly transition‐metal, elevated reaction temperature, and strong oxidants used in stoichiometric amounts . These raises concern regarding to atom economy and environmental issues . Therefore, the development of a green and sustainable approach for highly efficient preparation of carbazole framework remains a desirable task.…”