Palladium-Catalyzed Direct C–H Glycosylation of Free (<i>N</i>-H) Indole and Tryptophan by Norbornene-Mediated Regioselective C–H Activation

Chauhan, Neha Singh; Dubey, Aditi; Mandal, Pintu Kumar

doi:10.1021/acs.orglett.2c02537

Cited by 14 publications

(10 citation statements)

References 34 publications

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“…The mechanism study showed that the 2,3‐diglycosylation sequence of indole was C3, followed by C2. Based on these, Mandal group [28] described that naked N−H indole or tryptophan 60 synthesized a series of 2‐glycosylindoles and tryptophan‐C‐glycosides 62 through Pd catalyzed C−H glycosylation strategy. Norbornene plays an important role in this method, providing high chemoselectivity for indole by acting as an ortho ‐directing transient mediator 63 .…”

Section: Introductionmentioning

confidence: 99%

Synthesis of C‐Aryl Glycosides by C−H Functionalization

Gou

Zhu

Zhang

et al. 2023

Chemistry A European J

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In recent years, the synthesis of C‐aryl glycosides hrough C−H functionalization has attracted extensive attention of organic synthesis chemists due to its steps and atomic economy. In this concept, we systematically summarizes the synthesis of C‐aryl glycosides with diverse regioselectivity and diastereoselectivity from the perspective of C−H arylation of glycosides and C−H glycosylation of arenes. It can be found that a series of recently developed C−H glycosylation reactions have higher site‐selectivity and diastereomeric selectivity than Friedel–Crafts glycosylation reaction. The reaction conditions are milder, which can be compatible with acid‐sensitive protective groups, such as acetals or ketals, and the deprotection is more convenient. It can be seen that there are few reports on remote C−H glycosylation of aromatic hydrocarbons, which is a new field and needs further research. In addition, C−H glycosylation has a lot of shortcomings, which need to be further explored: a) the precise regulation of stereoselectivity in the reaction process also needs further optimization; b) the research on the reaction mechanism is almost limited to DFT calculation, and there is no exact experimental evidence. For key parts, such as the specific reaction mechanism between cyclo‐metal intermediates and glycosyl donors in ortho‐CAr−H glycosylation is still unclear; c) due to the fact that aryl glycoside compounds contain bare hydroxyl groups in practical applications, it is an urgent problem to realize the compatibility of glycoside substrates containing naked hydroxyl groups or to remove the protective groups on hydroxyl groups by a mild and efficient method after the reaction; d) In this rapidly developing field, we need to study a greener, more economical and more practical C−H glycosylation of arenes in the future, which will be conducive to the synthesis of C‐aryl glycosides with more biological application significance.

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Section: Introductionmentioning

confidence: 99%

Synthesis of C‐Aryl Glycosides by C−H Functionalization

Gou

Zhu

Zhang

et al. 2023

Chemistry A European J

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“…In 2021, Liang and co-workers successfully applied a structurally modified NBD for the synthesis of C4 -glycoside indole . Mandal’s group recently reported a palladium-catalyzed stereoselective synthesis of 2-glycosylindoles and tryptophan- C -glycosides via NBE-mediated C–H activation . Despite much great progress in this field, the development of a highly efficient, general, and convenient strategy leading to indolyl- C -glycosides from readily available starting materials is still highly valuable.…”

mentioning

confidence: 99%

Stereoselective Synthesis of Indolyl-C-glycosides Enabled by Sequential Aminopalladation and Heck Glycosylation of 2-Alkynylanilines with Glycals

Xiao,

Han,

Wan

et al. 2023

Org. Lett.

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“…Even if 4.0 equiv of glycosyl chlorides are used, the single bis- C -mannosylated indole could not be attained. Moreover, many elegant strategies employing transition-metal-catalyzed C–H glycosylation were subsequently developed by the groups of Chen and He, , Liang and Liu, Liu, Akermann, and others . But to the best of our knowledge, ferrocene derivatives have not been employed for this C–H glycosylation so far .…”

mentioning

confidence: 99%

Highly Stereoselective Synthesis of Bis-C-ferrocenyl Glycosides via Palladium-Catalyzed Directed C–H Glycosylation

Zhang

et al. 2023

Org. Lett.

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Conjugation of carbohydrates to ferrocene scaffolds is of great value in drug design, given the nontoxic and lipophilic nature of ferrocene. However, the efficient and stereoselective synthesis of C-ferrocenyl glycosides remains a challenge. Herein, we developed a Pd-catalyzed stereoselective C–H glycosylation to provide rapid access to sole bis-C-ferrocenyl glycosides in good to high yields (up to 98% yield) with exclusive stereoselectivity. A diverse range of glycosyl chlorides were well tolerated, including d-mannose, d-glucose, l-xylose, l-rhamnose, d-mannofuranose, and d-ribofuranose. Additionally, a mononuclear PdII intermediate was characterized by X-ray single-crystal diffraction, and might participate in the C–H palladation step.

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Palladium-Catalyzed Direct C–H Glycosylation of Free (N-H) Indole and Tryptophan by Norbornene-Mediated Regioselective C–H Activation

Cited by 14 publications

References 34 publications

Synthesis of C‐Aryl Glycosides by C−H Functionalization

Synthesis of C‐Aryl Glycosides by C−H Functionalization

Stereoselective Synthesis of Indolyl-C-glycosides Enabled by Sequential Aminopalladation and Heck Glycosylation of 2-Alkynylanilines with Glycals

Highly Stereoselective Synthesis of Bis-C-ferrocenyl Glycosides via Palladium-Catalyzed Directed C–H Glycosylation

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