Isolation and synthesis of biologically active carbazole alkaloids

Heterocyclic structural architectures occur in many bioactive natural products and synthetic drugs, and these structural units serve as important intermediates in organic synthesis. This Account documents our recent progress in the development of cascade reactions to construct complex carbocycles and heterocycles. We describe the rational design of cascade reactions and in-depth investigations of their mechanism as well as their applications in the synthesis of drugs, natural products, and related molecular analogs.Relying on knowledge about the dipole-type reactivity of sulfur ylides, we have developed three different types of cascade reactions: a [4 + 1] annulation/rearrangement cascade, a [4 + 1]/[3 + 2] cycloaddition cascade, and a Michael addition/N-alkylation cascade. Using these processes, we can generate oxazolidinones, fused heterocycles, and pyrrolines starting with simple and readily available substances such as nitroolefins and unsaturated imines. We have also developed corresponding enantiose...

Development of cascade reactions for the concise construction of diverse heterocyclic architectures.

An efficient rhenium‐catalyzed regioselective C−H bond alkenylation of indoles is reported. The protocol operates well for internal as well as terminal alkynes, affording products in good to excellent yields. Furthermore, a manganese‐catalyzed, acid free, regioselective C2‐alkenylation of indoles with internal alkynes is described. The directing groups can be easily removed after the reaction and the resulting products can be used as valuable building blocks for the synthesis of diverse heterocyclic compounds.

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Rhenium- and Manganese-Catalyzed Selective Alkenylation of Indoles

Olefins are essential building blocks in organic synthesis, the access to which from simple C−H substrates through catalysis of transition metals, in particular the earth's abundant ones meets the requirements of green and sustainable chemistry. Manganese‐catalyzed C−H olefination reactions have emerged as an efficient approach to olefins in recent years, complementary to traditional olefin synthesis. Varieties of alkynes, alkenes, allenes as well as alcohols are successfully applied to the Mn‐catalyzed reactions with C−H substrates, providing multisubstituted olefins bearing varied functional groups. This minireview presents great progresses newly achieved on manganese‐catalyzed C−H olefination reactions.

Manganese‐Catalyzed C−H Olefination Reactions

Five-Membered Heterocycles: Indole and Related Systems

Obtention d'indoles fonctionnalises, de carbazoles et de pyrrolo [3,4-c]- et benzo [c] carbazoles

M. Eitel

Papers

New regio- and stereocontrolled reactions of 2-vinylindoles with CC-dienophiles: Diels-Alder reactions, ene reactions, and Michael additions