ChemInform Abstract: Rhodium(III)‐Catalyzed Annulation of Azomethine Ylides with Alkynes via C—H Activation.

Chen, Yuye; Wang, Fen; Zhen, Wencui; Li, Xingwei

doi:10.1002/chin.201328095

Cited by 3 publications

(3 citation statements)

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“…162 A range of electron-donating and electron-withdrawing moieties on the aryl azomethine ylides were well tolerated in the reaction, generating the desired indene products 284 in good to high yield. A range of symmetric and unsymmetrical internal alkynes were evaluated and gave the desired products in good yield and with high regioselectivity.…”

Section: Additions To C=c π-Bonds Followed By Cyclization Upon Pomentioning

confidence: 99%

Transition-Metal-Catalyzed C–H Bond Addition to Carbonyls, Imines, and Related Polarized π Bonds

2016

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The transition metal-catalyzed addition of C–H bonds to carbonyls, imines and related polarized π-bonds has emerged as a particularly efficient and powerful approach for the construction of an incredibly diverse array of heteroatom substituted products. Readily available and stable inputs are typically employed, and reactions often proceed with very high functionality group compatibility and without the production of waste byproducts. Additionally, many transition metal-catalyzed C–H bond additions to polarized π-bonds occur within cascade reaction sequences to provide rapid access to a diverse array of different heterocyclic as well as carbocyclic products. This review highlights the diversity of transformations that have been achieved, catalysts that have been used, and types of products that have been prepared through the transition metal catalyzed addition of C–H bonds to carbonyls, imines and related polarized π-bonds.

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Section: Additions To C=c π-Bonds Followed By Cyclization Upon Pomentioning

confidence: 99%

Transition-Metal-Catalyzed C–H Bond Addition to Carbonyls, Imines, and Related Polarized π Bonds

2016

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“…Amides and imines are bifunctional DGs in that the nitrogen or oxygen donor is attached to an electrophilic CN or CO group, and their electrophilicity has been realized in C–H activation . The coupling of benzaldehyde-derived azomethine imines with alkynes follows a sequence of C–H activation, migratory insertion of the Rh–C bond into the alkyne, and nucleophilic attack of the Rh–C(alkenyl) bond into the electrophilic imine group, leading to indenamine products (Scheme ) . This type of reaction was initially reported using Re catalysts .…”

Section: Activation Of Arene Substratesmentioning

confidence: 99%

Substrate Activation Strategies in Rhodium(III)-Catalyzed Selective Functionalization of Arenes

2015

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The possibility of developing new methods for the efficient construction of organic molecules via disconnections other than traditional functional group transformations has driven the interest in direct functionalization of C-H bonds. The ubiquity of C-H bonds makes such transformations attractive, but they also pose several challenges. The first is the reactivity and selectivity of C-H bonds. To achieve this, directing groups (DGs) are often installed that can enhance the effective concentration of the catalyst, leading to thermodynamically stable metallacyclic intermediates. However, the presence of a pendant directing group in the product is often undesirable and unnecessary. This may account for the limitation of applications of C-H functionalization reactions in more common and general uses. Thus, the development of removable or functionalizable directing groups is desirable. Another key problem is that the reactivity of the resulting M-C bond can be low, which may limit the scope of the coupling partners and hence limit the reaction patterns of C-H activation reactions. While the first Cp*Rh(III)-catalyzed C-H activation of arenes was reported only 7 years ago, significant progress has been made in this area in the past few years. We began our studies in this area in 2010, and we and others have demonstrated that diversified catalytic functionalization of arenes can be realized using Cp*Rh(III) complexes with high reactivity, stability, and functional group compatibility. This Account describes our efforts to solve some of these challenges using Rh(III) catalysis. We fulfilled our design and activation of the arene substrates by taking advantage of the nucleophilicity, electrophilicity, oxidizing potential, and properties of a participating ligand of the directing groups when the arenes are coupled with relatively reactive unsaturated partners such as alkenes and alkynes. These in situ funtionalizable roles of the DG allowed extensive chemical manipulation of the initial coupled product, especially in the construction of a diverse array of heterocycles. In the coupling of arenes with polar coupling partners, the polar Rh(III)-C(aryl) bond showed higher reactivity as both an organometallic reagent and a nucleophilic aryl source. The polar coupling partners were accordingly activated by virtue of umpolung, ring strain, and rearomatization. All of these transformations have been made possible by integration of the higher reactivity, stability, and compatibility of Rh(III)-C bonds into catalytic systems. We have demonstrated that to date some of these transformations can be achieved only under rhodium catalysis. In addition, by means of stoichiometric reactions, we have gained mechanistic insights into the interactions between the Rh-C bond and the other coupling partners, which have opened new avenues in future direct C-H functionalization reactions.

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“…This strategy of C-H activation and [3+2] annulations has been further developed by others for the synthesis of other indenamides using Rh(III), Ru(II) and Mn catalysts [9]. In fact, this annulative strategy is not limited to indenamines, and the related syntheses of indenols and indenones have been achieved by Glorius et al [10], Cheng et al [11], Shi et al [12], our group [13], and others [14]. In all these systems, the imine, ketone, and amide functionality play a bifunctional role: the nucleophilic heteroatom offers chelation assistance, while the electrophilic C=E bond is then attacked by the resultant M-C bond (M=Ru, Ir, Rh, and Co) [15].…”

Section: Introductionmentioning

confidence: 96%

Rhodium(III)-catalyzed [3+2] annulative coupling between oximes and electron-deficient alkynes

Zhou

et al. 2015

Sci. China Chem.

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Rhodium(III)-catalyzed coupling between ketoximes and alkynes via C-H activation and annulation typically followed the [4+2] selectivity to afford isoquinolines. By designing alkynes bearing a highly electron-withdrawing group and under substrate control, we have successfully switched the selectivity of the coupling between oximes and alkynes to the alternative [3+2] annulation, leading to the efficient synthesis of indenamines. This process features good regioselectivity for both substrates, high efficiency, broad substrate scope, and excellent functional group tolerance.

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ChemInform Abstract: Rhodium(III)‐Catalyzed Annulation of Azomethine Ylides with Alkynes via C—H Activation.

Cited by 3 publications

References 1 publication

Transition-Metal-Catalyzed C–H Bond Addition to Carbonyls, Imines, and Related Polarized π Bonds

Transition-Metal-Catalyzed C–H Bond Addition to Carbonyls, Imines, and Related Polarized π Bonds

Substrate Activation Strategies in Rhodium(III)-Catalyzed Selective Functionalization of Arenes

Rhodium(III)-catalyzed [3+2] annulative coupling between oximes and electron-deficient alkynes

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