Directed Amination of Non‐Acidic Arene CH Bonds by a Copper–Silver Catalytic System

Tran, Ly Dieu; Roane, James; Daugulis, Olafs

doi:10.1002/ange.201300135

Cited by 106 publications

(29 citation statements)

References 61 publications

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“…Gratifyingly, aminoquinoline-directed, copper-catalyzed sp 2 C–H bond amination is possible (Scheme 10). 30 The amination is successful for both electron-rich and electron-poor amides, and the reaction tolerates most common substituents. In contrast to copper-promoted sulfenylation, where clean monofunctionalization was impossible, amination selectively delivers monofunctionalization products at the less sterically demanding position.…”

Section: Copper Catalysismentioning

confidence: 99%

Bidentate, Monoanionic Auxiliary-Directed Functionalization of Carbon–Hydrogen Bonds

2015

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CONSPECTUS In recent years, carbon–hydrogen bond functionalization has evolved from an organometallic curiosity to mainstream applications in the synthesis of complex natural products and drugs. The use of C–H bonds as a transformable functional group is advantageous because these bonds are the most abundant functionality in organic molecules. One-step conversion of these bonds to the desired functionality shortens synthetic pathways, saving reagents, solvents, and labor. Less chemical waste is generated as well, showing that this chemistry is environmentally beneficial. This Account describes the development and use of bidentate, monoanionic auxiliaries for transition-metal-catalyzed C–H bond functionalization reactions. The chemistry was initially developed to overcome the limitations with palladium-catalyzed C–H bond functionalization assisted by monodentate directing groups. By the use of electron-rich bidentate directing groups, functionalization of unactivated sp3 C–H bonds under palladium catalysis has been developed. Furthermore, a number of abundant base-metal complexes catalyze functionalization of sp2 C–H bonds. At this point, aminoquinoline, picolinic acid, and related compounds are among the most used and versatile directing moieties in C–H bond functionalization chemistry. These groups facilitate catalytic functionalization of sp2 and sp3 C–H bonds by iron, cobalt, nickel, copper, ruthenium, rhodium, and palladium complexes. Exceptionally general reactivity is observed, enabling, among other transformations, direct arylation, alkylation, fluorination, sulfenylation, amination, etherification, carbonylation, and alkenylation of carbon–hydrogen bonds. The versatility of these auxilaries can be attributed to the following factors. First, they are capable of stabilizing high oxidation states of transition metals, thereby facilitating the C–H bond functionalization step. Second, the directing groups can be removed, enabling their use in synthesis and functionalization of natural products and medicinally relevant substances. While the development of these directing groups presents a significant advance, several limitations of this methodology are apparent. The use of expensive second-row transition metal catalysts is still required for efficient sp3 C–H bond functionalization. Furthermore, a disadvantage is the need to install and subsequently remove the relatively expensive directing group.

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Section: Copper Catalysismentioning

confidence: 99%

Bidentate, Monoanionic Auxiliary-Directed Functionalization of Carbon–Hydrogen Bonds

2015

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“…47 Previously reported amination conditions 48 were used first to give a 21% yield observed of the reaction between 8-aminoquinoline 3-trifluoromethylbenzamide with 4- tert -butylphenol. Upon changing the oxidant to NMO/O 2 a yield of 67% was obtained, with an 88% yield reported using (CuOH) 2 CO 3 as a catalyst, K 2 CO 3 as base, and air as oxidant.…”

Section: C3–h-functionalizationmentioning

confidence: 99%

“…48 Initial studies focused on the reaction between 8-aminoquinoline p -methoxybenzamide ( 266 ) and morpholine with Cu(OAc) 2 as a catalyst in N -methylpyrrolidinone at 110 °C. Under these conditions coupling product 267 was obtained in 39% yield.…”

Section: C4–h-functionalizationmentioning

confidence: 99%

Recent advances in the C–H-functionalization of the distal positions in pyridines and quinolines

2015

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This review summarizes recent developments in the C–H-functionalization of the distal positions of pyridines, quinolines and related azaheterocycles. While the functionalization of the C2 position has been known for a long time and is facilitated by the proximity to N1, regioselective reactions in the distal positions are more difficult to achieve and have only emerged in the last decade. Recent advances in the transition metal-catalyzed distal C–H-functionalization of these synthetically-important azaheterocycles are discussed in detail, with the focus on the scope, site-selectivity and mechanistic aspects of the reactions.

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“…[1] Recently,transition-metal-catalyzed C À Hactivation/amination of arenes by an organometallic metal insertion approach has emerged as as ignificant area of research towards developing new methods for the synthesis of aryl amines. [12] Although the use of bidentate directing groups containing quinoline or oxazoline moieties substantially improved the scope of amine coupling partners,anilines, in particular,a re poor coupling partners in general, with N-alkyl anilines being completely inactive.S ignificant progress has also been made with Ir III catalysts to enable ortho-C À Haminations of benzamides with simple anilines and alkyl amines as coupling partners.H owever,t he involvement of an itrene insertion pathway excluded the use of secondary amines (Scheme 1b). While these reactions have established the feasibility of the C À Hi nsertion and C À Nr eductive elimination steps with an umber of synthetically useful directing groups,t he use of chalcogenide-type amino electrophiles is not ideal owing to the cost and limited scope of amino groups that can be introduced.…”

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Ligand‐Promoted Rhodium(III)‐Catalyzed ortho‐C−H Amination with Free Amines

Wang

Zhang

et al. 2017

Angewandte Chemie

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Ligand development for rhodium(III)-catalyzed CÀHa ctivation reactions has largely been limited to cyclopentadienyl (Cp) based scaffolds.2 -Methylquinoline has now been identified as af easible ligand that can coordinate to the metal center of Cp*RhCl to accelerate the cleavage of the C À H bond of N-pentafluorophenylbenzamides,p roviding an ew structural lead for ligand design. The compatibility of this reaction with secondary free amines and anilines also overcomes the limitations of palladium(II)-catalyzed CÀHamination reactions.Aryl amines are privileged structural motifs in modern drug discovery. [1] Recently,transition-metal-catalyzed C À Hactivation/amination of arenes by an organometallic metal insertion approach has emerged as as ignificant area of research towards developing new methods for the synthesis of aryl amines. [2] Ar edox catalytic cycle proceeding through metal insertion and subsequent oxidation with chalcogenide-type (N À Xs pecies) N À Oo rN À halogen amino donors (such as N-benzoate alkylamines, N-chloroamines, N-hydroxycarbamates, O-acylhydroxylamines,n itrosobenzenes,a zides,a nd 1,4,2-dioxazol-5-one) has been extensively explored with Pd II , [3,4] Ir III , [5] Rh III , [6] Ru II , [7] Cu II , [8] Co II , [9] and Fe II [10] catalysts (Scheme 1a). While these reactions have established the feasibility of the C À Hi nsertion and C À Nr eductive elimination steps with an umber of synthetically useful directing groups,t he use of chalcogenide-type amino electrophiles is not ideal owing to the cost and limited scope of amino groups that can be introduced. Thus the development of ad irect intermolecular coupling of arenes with free amines as nucleophiles is as ignificant task.Although C À Hc ouplings with organometallic carbon nucleophiles by Pd II /Pd 0 catalysis have been developed, [11] analogous couplings using strongly coordinating free amines remain an unmet challenge.O nt he other hand, CÀH amination reactions with secondary and primary amines have been made possible with Cu II ,N i II ,a nd Co III catalysts (Scheme 1b). [12] Although the use of bidentate directing groups containing quinoline or oxazoline moieties substantially improved the scope of amine coupling partners,anilines, in particular,a re poor coupling partners in general, with N-alkyl anilines being completely inactive.S ignificant progress has also been made with Ir III catalysts to enable ortho-C À Haminations of benzamides with simple anilines and alkyl amines as coupling partners.H owever,t he involvement of an itrene insertion pathway excluded the use of secondary amines (Scheme 1b). [13] Moreover,R h III -catalyzed intermolecular CÀHa mination is uniformly limited to preactivated amine coupling partners. [6] These limitations point to the need for new ligands for Rh III catalysts.H erein, we report the identification of an ew quinoline ligand that promotes Rh IIIcatalyzed ortho-C À Ha mination reactions with free amines. Notably,b oth secondary amines and primary anilines are compatible with this newly developed ca...

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Directed Amination of Non‐Acidic Arene CH Bonds by a Copper–Silver Catalytic System

Cited by 106 publications

References 61 publications

Bidentate, Monoanionic Auxiliary-Directed Functionalization of Carbon–Hydrogen Bonds

Bidentate, Monoanionic Auxiliary-Directed Functionalization of Carbon–Hydrogen Bonds

Recent advances in the C–H-functionalization of the distal positions in pyridines and quinolines

Ligand‐Promoted Rhodium(III)‐Catalyzed ortho‐C−H Amination with Free Amines

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