Practical Ni-Catalyzed Aryl–Alkyl Cross-Coupling of Secondary Redox-Active Esters

Cornellà, Josep; Edwards, Jacob T.; Qin, Tian; Kawamura, Shuhei; Wang, Jie; Pan, Chung Mao; Gianatassio, Ryan; Schmidt, Michael A.; Eastgate, Martin D.; Baran, Phil S.

doi:10.1021/jacs.6b00250

Cited by 378 publications

(237 citation statements)

References 61 publications

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“…The scalability was also evaluated using 42 and it was found to proceed smoothly to deliver 3 on a gram-scale (Scheme 2B). In accord with our previous findings, [3,4] the reaction of redox-active esters with in situ generated low valent Ni species generates radical intermediates as evidenced by the cyclopropane-opened product 44 derived from 43 (Scheme 2C). …”

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confidence: 92%

Nickel‐Catalyzed Cross‐Coupling of Redox‐Active Esters with Boronic Acids

et al. 2016

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A transformation analogous in simplicity and functional group tolerance to the venerable Suzuki cross-coupling between alkyl-carboxylic acids and boronic acids is described. This Ni-catalyzed reaction relies upon the activation of alkyl carboxylic acids as their redox-active ester derivatives, specifically N-hydroxy-tetrachlorophthalimide (TCNHPI), and proceeds in a practical and scalable fashion. The inexpensive nature of the reaction components (NiCl2•6H2O – $9.5/mol, Et3N) coupled to the virtually unlimited commercial catalog of available starting materials bodes well for its rapid adoption.

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confidence: 92%

Nickel‐Catalyzed Cross‐Coupling of Redox‐Active Esters with Boronic Acids

et al. 2016

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“…Nevertheless, the scope of amine nucleophiles is limited to carbazoles 16,18 and amides 17,19 . Alternative, formal C-N coupling of alkyl electrophiles via the addition of alkyl radicals to nitroarenes has been reported 20,21 .The group of Baran has recently trailblazed the use of redox-active esters derived from alkyl carboxylic acids as superior surrogates of alkyl halides in decarboxylative C-C cross-coupling reactions [22][23][24] . Extension to a decarboxylative carbon-heteroatom, particularly C-B bond formation has also been reported 19,[25][26][27][28][29] .…”

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confidence: 99%

“…The group of Baran has recently trailblazed the use of redox-active esters derived from alkyl carboxylic acids as superior surrogates of alkyl halides in decarboxylative C-C cross-coupling reactions [22][23][24] . Extension to a decarboxylative carbon-heteroatom, particularly C-B bond formation has also been reported 19,[25][26][27][28][29] .…”

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confidence: 99%

“…The activation principle of redox-active esters originates from amide-bond synthesis; thus, amide formation can compete when amine nucleophiles are used. Moreover, decarboxylative C-C coupling reactions of redox-active esters were, until now, all initiated by electron transfer from an organometallic nickel or iron species [22][23][24]34 ; the analogous electron transfer from metal amido species was unprecedented. The result of the reaction of cyclohexyl N-hydroxyphthalimide (NHPI) ester 1a with aniline 2a under conditions similar to those of Baran decarboxyative C-C coupling 22,23 seemed to substantiate these concerns (Fig.…”

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confidence: 99%

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Decarboxylative C(sp3)–N cross-coupling via synergetic photoredox and copper catalysis

et al. 2018

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A mines are one of the most important structural motifs in pharmaceuticals, agrochemicals and organic materials 1,2 . Alkylation and reductive amination reactions are still commonly used to prepare and modify amines, and new methods derived from reductive amination, such as the borrowing hydrogen 3 strategy, have been reported [4][5][6][7] . Nevertheless, the most significant development in amine synthesis has been transition-metal-catalysed C-N coupling of aryl electrophiles (halides and pseudo halides) with amine nucleophiles [8][9][10][11] (Fig. 1a). The C-N coupling of alkyl electrophiles, however, is largely under-developed (Fig. 1a). A perceived difficulty is β -hydrogen elimination from a metal alkyl intermediate originated from oxidative addition of the alkyl electrophile, which has posed considerable challenges in analogous C-C crosscoupling of alkyl electrophiles [12][13][14] . Moreover, the product-yielding C(sp 3 )-N reductive elimination step is rarely demonstrated 15 . A notable exception is the light-induced, copper-catalysed C-N coupling of alkyl halides recently developed [16][17][18] . Nevertheless, the scope of amine nucleophiles is limited to carbazoles 16,18 and amides 17,19 . Alternative, formal C-N coupling of alkyl electrophiles via the addition of alkyl radicals to nitroarenes has been reported 20,21 .The group of Baran has recently trailblazed the use of redox-active esters derived from alkyl carboxylic acids as superior surrogates of alkyl halides in decarboxylative C-C cross-coupling reactions [22][23][24] . Extension to a decarboxylative carbon-heteroatom, particularly C-B bond formation has also been reported 19,[25][26][27][28][29] . The key attributes of alkyl carboxylic acids 30,31 are their unparalleled availability, stability and non-toxic nature, which are in stark contrast with alkyl halides, ketones and aldehydes. While several precedents of decarboxylative imidation 32 and amination 19,33 are known, they are limited to a narrow scope of very special substrates or intramolecular reactions. A general metal-catalysed decarboxylative C-N coupling of redox-active esters with anilines will provide valuable methodology for the synthesis of alkylated anilines (Fig. 1b), which requires alkyl halides and carbonyl compounds 6 as starting reagents using the currently standard methods of alkylation and reductive amination, respectively. Further foreseen advantages of such a decarboxylative amination include applicability to bulky primary and secondary alkyl groups and immunity to over-alkylation, both of which are major limitations of direct alkylation (Fig. 1b). Despite its conceptual simplicity and resemblance to decarboxylative C-C coupling, the intermolecular decarboxylative C-N coupling of redoxactive esters poses significant hurdles. The activation principle of redox-active esters originates from amide-bond synthesis; thus, amide formation can compete when amine nucleophiles are used. Moreover, decarboxylative C-C coupling reactions of redox-active esters were, until now, all init...

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“…The dominant metals in this field are palladium, 1 copper, 2 and nickel, 3 whereas other transition metals such as iron are less explored. However, iron is an inexpensive, nontoxic and environmentally benign transition metal that in the past few years has gained new impetus.…”

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confidence: 99%

A Synthesis of Substituted α-Allenols via Iron-Catalyzed Cross-Coupling of Propargyl Carboxylates with Grignard Reagents

2016

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α-Allenols are attractive and versatile compounds whose preparation can be a nontrivial task. In this Letter, we provide a method for the prompt synthesis of substituted α-allenols via a catalytic cross-coupling reaction which makes use of a nontoxic and cost-effective iron catalyst. The catalyst loading is typically as low as 1–5 mol %. The mild reaction conditions (−20 °C) and the short reaction time (15 min) allow for the presence of a variety of functional groups. Moreover, the reaction was shown to be scalable up to gram-scale and the propargyl substrates are readily accessible by a one-pot synthesis.

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Practical Ni-Catalyzed Aryl–Alkyl Cross-Coupling of Secondary Redox-Active Esters

Cited by 378 publications

References 61 publications

Nickel‐Catalyzed Cross‐Coupling of Redox‐Active Esters with Boronic Acids

Nickel‐Catalyzed Cross‐Coupling of Redox‐Active Esters with Boronic Acids

Decarboxylative C(sp3)–N cross-coupling via synergetic photoredox and copper catalysis

A Synthesis of Substituted α-Allenols via Iron-Catalyzed Cross-Coupling of Propargyl Carboxylates with Grignard Reagents

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