Iron(III)/Iodine‐Catalyzed C(<i>sp</i><sup>2</sup>)H Activation of α,β‐Unsaturated Aldehydes/Ketones with Amidines: Synthesis of 1,2,4,5‐Tetrasubstituted Imidazoles

Wu, Ping; Qu, Jinpeng; Li, Yaxuan; Guo, Xin; Tang, Dong; Meng, Xu; Yan, Rulong; Chen, Baohua

doi:10.1002/adsc.201500701

Cited by 43 publications

(19 citation statements)

References 84 publications

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“…also independently developed an excellent methodology for the synthesis of imidazole derivatives from the α , β ‐unsaturated aldehydes/ketones (Scheme 36). [39] During the optimization of the reaction conditions, they found that the best result was obtained by carrying out the reaction in presence of FeCl 3 .6H 2 O (10 mol%), 1,10‐phenanthroline (10 mol%) and I 2 (2.5 mol%) in 1,2‐dichlorobenzene at 110 °C under aerobic conditions. Although, the reaction also proceeded in absence of I 2 however the presence of I 2 increased the yield dramatically.…”

Section: Synthesis Of Heterocycles Via Oxidative Couplingmentioning

confidence: 99%

Application of Conjugated Carbonyls in the Synthesis of Heterocycles via Oxidative Cycloaddition and Cyclization Reactions

et al. 2020

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Synthesis of pharmaceutically active heterocycles is always appealing as the majority of the widely used drugs contain heterocyclic moieties as their core structure. So, the straightforward construction of heterocycles from readily available/accessible reagents is one of the prime targets of the synthetic chemists. In this context, CÀ H functionalization has emerged as an effective tool for the designing and synthesis of various heterocyclic moieties as it offers a straightforward and step-economic pathway. On the other hand, the readily available/accessible conjugated carbonyls are well-known reagents for the construction of carbocycles and heterocycles over the years. However, the employment of CÀ H functionalization of the two CÀ H bonds of the conjugated alkene in carbocycle/heterocycle synthesis was not so explored. In the last decade, much focus has been paid on the synthesis of various pharmaceutically active heterocycles through CÀ H bond functionalization of α,β-unsaturated aldehydes/ketones. These protocols have been developed through either oxida-tive coupling of conjugated carbonyls with suitable coupling partners or intramolecular CÀ H bond functionalization of conjugated carbonyls. In this review, we will discuss all the methodologies developed for the synthesis of heterocycles employing intermolecular CÀ H bond functionalization of conjugated carbonyls. The mechanistic pathways and usefulness of the methodologies will be also highlighted.

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Section: Synthesis Of Heterocycles Via Oxidative Couplingmentioning

confidence: 99%

Application of Conjugated Carbonyls in the Synthesis of Heterocycles via Oxidative Cycloaddition and Cyclization Reactions

et al. 2020

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“…In 2015, they developed a facile iron(III)‐catalyzed C−H amination to access highly substituted imidazoles with good to excellent yields using α , β ‐unsaturated aldehydes/ketones and amidines as starting materials (Scheme 15). [38a] The additive, I 2 , played a dual role in this transformation involving the function II and III . On the one hand, I 2 could prompt the transformation of an intermediate I52 into I53 with the release of HI, which followed by an intramolecular nucleophilic cyclization to form an intermediate I54 .…”

Section: Oxidizing Component‐induced Reactionsmentioning

confidence: 99%

Acid‐Acid‐Catalyzed Tandem Reactions Driven by an Additive‐Like Component

Chen

Bai

et al. 2020

The Chemical Record

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Acid‐catalyzed tandem reactions with auto‐tandem catalysis are effective for simplifying organic synthesis. However, some of the reported reactions were established based on the use of well‐designed substrate with complex structure. In some cases, owing to the existence of a big gap between each catalytic cycle, it is hard to bind all the individual reaction steps to be a peaceful sequence. To enrich the diversity and also to strengthen the practical usefulness of the methodology developed by auto‐tandem catalysis, an additive‐like component was added to induce acid‐acid‐catalyzed tandem reaction. During the reaction, the additive‐like component acted either as an activator to increase the reactivity of the starting material or a hided reagent to enable successful transformation of the intermediate. Many novel tandem reactions were established in a one‐pot manner with the aid of this strategy. Importantly, this strategy not only allows the use of simple and commercially available chemicals as substrates, but also possesses multiple merits, such as simplifying operation, lowering waste generation and enhancing synthetic efficiency and atom‐economy. A summarization of the additive‐like component‐induced auto‐tandem catalysis with an acid catalyst was given in this review, in which many acid‐acid‐catalyzed tandem reactions were discussed. The reported additive‐like components were classified as three types: oxidative type, reductive type and neutral type depending on their mechanisms in assisting the establishment of acid‐acid‐catalyzed tandem reactions. Many examples were collected and analyzed from the viewpoints of simplifying the synthesis and manifesting their superior and distinct functionalities of the additives. A perspective of this concept was also given at the end of this review.

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“…[187] Still in 2015, Chen and coworkers described efficient regioselective syntheses of 5-aroyl-1,2,4triaryl-1H-imidazoles 56 via iron(III)/iodinecatalyzed Csp 2 -H activation of a,b-unsaturated ketones/aldehydes with amidines. [190] . Compounds 56 were generally obtained in good to excellent yields by treatment of 1 equiv of a,b-unsaturated ketones 152 with 1.2 equiv of amidines 151 in 1,2dichlorobenzene (1,2-DCB) in the presence of 10 mol% FeCl3×××6H2O, 2.5 mol% I2 and 10 mol% 1,10phenanthroline (1,10-phen) (Scheme 83).…”

Section: Scheme 81 Fecl3/i2-catalyzed Aerobic Oxidative Coupling Reaction Of Amidines 151 With Chalcones 152mentioning

confidence: 99%

Catalytic Synthesis of 1,2,4,5‐Tetrasubstituted 1H‐Imidazole Derivatives: State of the Art

et al. 2019

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1,2,4,5-Tetrasubstituted-1H-imidazoles are a large family of heteroarene derivatives that are known to include natural products isolated from marine sponges and synthetic compounds possessing a broad range of biological and pharmacological properties. Consequently, a great deal of attention has been given to the synthesis of these heteroarenes and reviews covering some synthetic aspects of this topic have been published in recent years. However, none of these reviews provides a comprehensive overview of the several catalytic methods developed in the literature for the preparation of this important class of heteroarenes. This article review with 469 references, 63% of them being related to the period 2010-2017, aims to provide an updated critical picture of the catalytic processes reported in the literature up to the end of 2017 for the synthesis of 1,2,4,5-tetrasubstituted-1H-imidazoles illustrating these protocols and their characteristic features such as scope, efficiency, versatility, and limitations. The review also summarizes the mechanisms of the catalytic processes proposed for many of the reported processes.

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Iron(III)/Iodine‐Catalyzed C(sp²)H Activation of α,β‐Unsaturated Aldehydes/Ketones with Amidines: Synthesis of 1,2,4,5‐Tetrasubstituted Imidazoles

Cited by 43 publications

References 84 publications

Application of Conjugated Carbonyls in the Synthesis of Heterocycles via Oxidative Cycloaddition and Cyclization Reactions

Application of Conjugated Carbonyls in the Synthesis of Heterocycles via Oxidative Cycloaddition and Cyclization Reactions

Acid‐Acid‐Catalyzed Tandem Reactions Driven by an Additive‐Like Component

Catalytic Synthesis of 1,2,4,5‐Tetrasubstituted 1H‐Imidazole Derivatives: State of the Art

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Iron(III)/Iodine‐Catalyzed C(sp2)H Activation of α,β‐Unsaturated Aldehydes/Ketones with Amidines: Synthesis of 1,2,4,5‐Tetrasubstituted Imidazoles

Cited by 43 publications

References 84 publications

Application of Conjugated Carbonyls in the Synthesis of Heterocycles via Oxidative Cycloaddition and Cyclization Reactions

Application of Conjugated Carbonyls in the Synthesis of Heterocycles via Oxidative Cycloaddition and Cyclization Reactions

Acid‐Acid‐Catalyzed Tandem Reactions Driven by an Additive‐Like Component

Catalytic Synthesis of 1,2,4,5‐Tetrasubstituted 1H‐Imidazole Derivatives: State of the Art

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Iron(III)/Iodine‐Catalyzed C(sp²)H Activation of α,β‐Unsaturated Aldehydes/Ketones with Amidines: Synthesis of 1,2,4,5‐Tetrasubstituted Imidazoles