Transition Metal‐Catalyzed Benzannulation towards Naturally Occurring Carbazole Alkaloids

Zhang, Xue; Ma, Shengming

doi:10.1002/ijch.201700034

Cited by 14 publications

(3 citation statements)

References 66 publications

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“…Along with that, as mentioned earlier, the limitations are also overcome by the typical use of Rh-benzannulation protocols . The benzannulation term was originally adopted from the Latin word indicating the formation of two new bonds in the rapid “anellus method” . Gratifyingly, Rh-catalyzed benzannulations are promising and scalable techniques in modern organic synthesis pursuits in which new rings are formed over a pre-existing scaffold efficiently. − Additionally, Rh-catalyzed pathways are also known to foster many benefits, including no requirement of prefunctionalization, chemodivergent–convergent pathway, and straightforward and rapid access to molecular complexity in a one-shot manner.…”

Section: Introductionmentioning

confidence: 99%

[RhCp*Cl₂]₂-Catalyzed Indole Functionalization: Synthesis of Bioinspired Indole-Fused Polycycles

Singh Chauhan,

Mali,

Dua

et al. 2023

ACS Omega

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Polycyclic fused indoles are ubiquitous in natural products and pharmaceuticals due to their immense structural diversity and biological inference, making them suitable for charting broader chemical space. Indole-based polycycles continue to be fascinating as well as challenging targets for synthetic fabrication because of their characteristic structural frameworks possessing biologically intriguing compounds of both natural and synthetic origin. As a result, an assortment of new chemical processes and catalytic routes has been established to provide unified access to these skeletons in a very efficient and selective manner. Transition-metal-catalyzed processes, in particular from rhodium(III), are widely used in synthetic endeavors to increase molecular complexity efficiently. In recent years, this has resulted in significant progress in reaching molecular scaffolds with enormous biological activity based on core indole skeletons. Additionally, Rh(III)-catalyzed direct C–H functionalization and benzannulation protocols of indole moieties were one of the most alluring synthetic techniques to generate indole-fused polycyclic molecules efficiently. This review sheds light on recent developments toward synthesizing fused indoles by cascade annulation methods using Rh(III)-[RhCp*Cl2]2-catalyzed pathways, which align with the comprehensive and sophisticated developments in the field of Rh(III)-catalyzed indole functionalization. Here, we looked at a few intriguing cascade-based synthetic designs catalyzed by Rh(III) that produced elaborate frameworks inspired by indole bioactivity. The review also strongly emphasizes mechanistic insights for reaching 1–2, 2–3, and 3–4-fused indole systems, focusing on Rh(III)-catalyzed routes. With an emphasis on synthetic efficiency and product diversity, synthetic methods of chosen polycyclic carbocycles and heterocycles with at least three fused, bridged, or spiro cages are reviewed. The newly created synthesis concepts or toolkits for accessing diazepine, indol-ones, carbazoles, and benzo-indoles, as well as illustrative privileged synthetic techniques, are included in the featured collection.

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Section: Introductionmentioning

confidence: 99%

[RhCp*Cl₂]₂-Catalyzed Indole Functionalization: Synthesis of Bioinspired Indole-Fused Polycycles

Singh Chauhan,

Mali,

Dua

et al. 2023

ACS Omega

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“…In 1987, the first homogeneous gold-catalyzed addition of nucleophiles to alkynes was realized by the group of Utimoto using sodium tetrachloroaurate dihydrate. , One decade later, Teles et al and Tanaka et al demonstrated the possibility of activating alkynes using gold(I) complexes. From that point, the field of gold(I) catalysis started to gain momentum year after year and still today remains one of the most active areas of research in organometallic chemistry. , This comes as a consequence of the ability of gold(I) complexes to activate π bonds in a very selective manner. − Its potential, attributed partially to relativistic effects, is illustrated by the wide molecular complexity − that can be built through the gold(I)-catalyzed cycloisomerization of enynes (Scheme ). − …”

Section: Introductionmentioning

confidence: 99%

Gold-Catalyzed Synthesis of Small Rings

et al. 2020

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Three- and four-membered rings, widespread motifs in nature and medicinal chemistry, have fascinated chemists ever since their discovery. However, due to energetic considerations, small rings are often difficult to assemble. In this regard, homogeneous gold catalysis has emerged as a powerful tool to construct these highly strained carbocycles. This review aims to provide a comprehensive summary of all the major advances and discoveries made in the gold-catalyzed synthesis of cyclopropanes, cyclopropenes, cyclobutanes, cyclobutenes, and their corresponding heterocyclic or heterosubstituted analogs.

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“…The assembly of the core structures of such compounds are often achieved by organic transformations of these enones (Figure ). − Remote functionalization, particularly at the γ-positions of dienolates and ε-positions of trienolates, is rather inefficient due to the reduced nucleophilicity at these positions when compared to α-enolates …”

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confidence: 99%

Palladium-Mediated Remote Functionalization in γ- and ε-Arylations and Alkenylations of Unblocked Cyclic Enones

2019

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We report herein an extensive investigation of simple and regioselective endo-as well as exo-γ-arylations of silyldienol ethers of unblocked cyclic enones with the utilization of palladium-catalyzed, modified Kuwajima−Urabe conditions. We have also successfully explored a new exo-ε-arylation of silyl-trienol ethers of π-extended cyclic enones. In addition, we also report, herein, exclusive γand ε-alkenylation of silyl-dienol and silyl-trienol ethers of cyclic enones.

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Transition Metal‐Catalyzed Benzannulation towards Naturally Occurring Carbazole Alkaloids

Cited by 14 publications

References 66 publications

[RhCp*Cl₂]₂-Catalyzed Indole Functionalization: Synthesis of Bioinspired Indole-Fused Polycycles

[RhCp*Cl₂]₂-Catalyzed Indole Functionalization: Synthesis of Bioinspired Indole-Fused Polycycles

Gold-Catalyzed Synthesis of Small Rings

Palladium-Mediated Remote Functionalization in γ- and ε-Arylations and Alkenylations of Unblocked Cyclic Enones

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Transition Metal‐Catalyzed Benzannulation towards Naturally Occurring Carbazole Alkaloids

Cited by 14 publications

References 66 publications

[RhCp*Cl2]2-Catalyzed Indole Functionalization: Synthesis of Bioinspired Indole-Fused Polycycles

[RhCp*Cl2]2-Catalyzed Indole Functionalization: Synthesis of Bioinspired Indole-Fused Polycycles

Gold-Catalyzed Synthesis of Small Rings

Palladium-Mediated Remote Functionalization in γ- and ε-Arylations and Alkenylations of Unblocked Cyclic Enones

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Product

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[RhCp*Cl₂]₂-Catalyzed Indole Functionalization: Synthesis of Bioinspired Indole-Fused Polycycles

[RhCp*Cl₂]₂-Catalyzed Indole Functionalization: Synthesis of Bioinspired Indole-Fused Polycycles