Directly Bridging Indoles to 3,3′‐Bisindolylmethanes by Using Carboxylic Acids and Hydrosilanes under Mild Conditions

Qiao, Chang; Liu, Xiaofang; Fu, Hongyong; Yang, Haopeng; Zhang, Zhibo; He, Ling

doi:10.1002/asia.201800766

Cited by 19 publications

(7 citation statements)

References 55 publications

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“…The mechanism was also described in Scheme 6. In the same year, He et al [49] described similar metal-free protocol of B(C 6 F 5 ) 3 -catalyzed synthesis of the symmetrical 3,3'-BIMs. Instead of aldehydes, more readily available, abundant, stable and easy-to-handle carboxylic acids were treated as alkylating reagents.…”

Section: Synthetic Approaches To Symmetrical 3 3'-bimsmentioning

confidence: 99%

Recent Advance on the Synthesis of 3,3'-Bisindolylmethane Derivatives under Transition-Metal-Free Catalytic Conditions

Zhang¹,

Liu²,

Zong³

et al. 2021

Chinese Journal of Organic Chemistry

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3, compounds are important indole alkyloads and their units are widely found in various natural products, functional materials and synthetic pharmaceutical compounds. Due to diverse biological activities and functionalities, for instance, antioxidant, anti-inflammatory, antiangiogenic, anti-bacterial and anti-cancer etc., the construction of 3,3'-BIMs is raised considerable concerns. Conventional methods especially focused on symmetrical 3,3'-BIMs were the condensition of indoles with carbonyl compounds via Friedel-Crafts pathway in the presence of Brønsted acids or Lewis acids. However, the utilization of transtion metals led the residue into the products and environmental contamination. The recent advance on the synthesis of 3,3'-BIMs since 2010, mainly concerned on the approaches and corresponding mechanism to prepare symmetrical and unsymmetrical 3,3'-BIMs under transition-metal-free conditions is summarized and discussed, aiming to provide important theoretical evidence and techinical support for further biological evaluations on desired compounds.

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Section: Synthetic Approaches To Symmetrical 3 3'-bimsmentioning

confidence: 99%

Recent Advance on the Synthesis of 3,3'-Bisindolylmethane Derivatives under Transition-Metal-Free Catalytic Conditions

Zhang¹,

Liu²,

Zong³

et al. 2021

Chinese Journal of Organic Chemistry

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“…used the property of boranes to selectively reduce carboxylic acids to aldehydes and their Lewis acidity that promotes the Friedel Crafts reaction between indoles and aldehydes for to synthesize 3,3'-methylene bridged indoles using formic acid as the C-1 synthon. [51] They also employed hydride transfer property of trialkyl/aryl boron hydrides for the same. The group successfully showed that 3,3'-methylene bridged indoles can be successfully generated from indoles and formic acid in the presence of B(C 6 F 5 ) 3 and triethylsilyl hydride (Et 3 SiH) under neat conditions at room temperature (Scheme 44).…”

Section: Methanol As a Methylene Donormentioning

confidence: 99%

“…The formation of this is attributed to the decomposition of 3indoletosylhydrazole under the action of the base. This is followed by the formation of the metallacarbene complex (51) with the removal of N2 gas. The metallacarbene complex (51) is subsequently attacked by deprotonated indole (53) formed as a result of deprotonation of indole by Cs 2 CO 3 to form the intermediate (52).…”

Section: Scheme 43 Hydrogen Borrowing Strategy For Using Methanol Asmentioning

confidence: 99%

Methylene Surrogates for the Synthesis of 3,3’‐Diindolylmethanes

Sarmah

Bora

2020

ChemistrySelect

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Di(1H‐indol‐3‐yl)methanes (DIMs) and their derivatives are one of the highly essential indole derivatives with a broad spectrum of biological activities. The scaffold involves two indole/substituted indole moieties connected to each other via a methenyl bridge generally at the 3,3’ positions, as well as 2,2’ and 2,3’ positions. Synthesis of such moieties with the use of easily available chemicals and process is highly desirable for its tremendous importance in the fields of organic and medicinal chemistry. Herein, we review the synthesis of 3,3’‐methylene bridged indoles with the use of some methylene surrogates under various chemical and catalytic conditions.

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“…The use of 21.2 as key intermediates in tandem reactions afforded aldehydes 21.3 , alcohols 21.4 , alkyl halides 21.6 , thioethers 21.7 , 21.9 and alkylaminess 21.10 . In 2018, the He group utilized arylacetic acids as the benzyl source in the construction of 3,3’‐bisindolylmethanes 21.11 (Eq. 21‐2).…”

Section: Deprotonationmentioning

confidence: 99%

Arylacetic Acids in Organic Synthesis

et al. 2019

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Arylacetic acids are widely used in organic reactions and their recent advances are summarized in six categories according to their triggered pathways: (1) the acid as directing group in ortho-or meta-CÀ H activation; (2) decarboxylation; (3) deprotonation; (4) nucleophilic methylenes; (5) nucleophilic acids; (6) electrophilic acids. Reactions with alkenes, alkynes, aldehydes, amines, water, Grignard reagents, silanes and so forth are discussed. We hope this Minireview will promote future research in this area. Recently, the Zeng group [3g] reported a weakly coordinationassisted alkynylation of arylacetic acids with iridium catalysis under air atmosphere (Eq. 2-2). It was supported the sixmembered ring cycloiridiated 2.5 acted as the key intermediate. The alkynylation of indole, thiophene, pyrrole, and benzo[b] thiophene afforded better yields than phenylacetic acids. The acid moiety could also participated in the intramolecular ortho-CÀ H activation, which was developed by the Shi group to obtain lactonization 2.6 (Eq. 2-3) (Scheme 2). Meta-CÀ H ArylationThe study of Yu group [3e] in 2017 revealed a successful control of meta selectivity 3.1 of arylation from aryl iodides (Eq. 3-1). The use of mono-protected 3-amino-2-hydroxypyridine (as ligand) and 2-carbomethoxynorbornene (NBE-CO 2 Me) were crucial. In the absence of NBE-CO 2 Me, only ortho-arylated product was obtained. This method was still efficient in a gramsale (Scheme 3). Decarboxylation Decarboxylative CouplingAs shown in Scheme 4, the decarboxylation could generate benzyl radicals 4.1. Then, direct couplings of 4.1 with diverse [ + ] These authors contributed equally. Scheme 1. Six categories based on triggered mechanism. 2 3 4 5 6 7 8 . Passerini Three-Component ReactionThe Passerini reaction was the oldest multicomponent reaction (MCR) [37d] in which isocyanides, carboxylic acids and aldehydes were used. It was powerful for the rapid construction of complex molecules. The tactic to expand the scope of Passerini reaction was to use surrogates of the carbonyl partners. As described in Scheme 51, syn-chlorooximes, [37b] diazoketones, [37c] alcohols, [37d,e] azirines [37f] and isatins [37g] could be employed instead of aryl or alkyl aldehydes [37a] (Scheme 51). Besides, in 2018, Zhang and co-workers [37] have firstly reported asymmetric phosphoric acid-catalyzed four-component Ugi reaction, which Scheme 45. BTM-catalyzed cycloaddition. Scheme 46. HBTM-catalyzed cycloaddition. Scheme 47. TFA-catalyzed reaction. Scheme 48. Friedel-Crafts triggered tandem reactions. Scheme 49. C-acylation of 1,3-diones. Scheme 50. C-acylation of 1,3-indandiones.

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Directly Bridging Indoles to 3,3′‐Bisindolylmethanes by Using Carboxylic Acids and Hydrosilanes under Mild Conditions

Cited by 19 publications

References 55 publications

Recent Advance on the Synthesis of 3,3'-Bisindolylmethane Derivatives under Transition-Metal-Free Catalytic Conditions

Recent Advance on the Synthesis of 3,3'-Bisindolylmethane Derivatives under Transition-Metal-Free Catalytic Conditions

Methylene Surrogates for the Synthesis of 3,3’‐Diindolylmethanes

Arylacetic Acids in Organic Synthesis

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