Visible‐Light‐Mediated Chan–Lam Coupling Reactions of Aryl Boronic Acids and Aniline Derivatives

Yoo, Woo‐Jin; Tsukamoto, Tatsuhiro; Kobayashi, Shū

doi:10.1002/anie.201500074

Cited by 140 publications

(74 citation statements)

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“…During the past years, great progress on the palladium-based modied Ullmann and Goldberg coupling reactions protocols have been made, 42 but the drawbacks of the catalyst systems, such as air sensitivity and high cost, limit their applications. On the other hand, in 1998, the groups of Chan, Evans, and Lam independently developed Cu-mediated oxidative amination of aryl boronic acids with amines and other nucleophiles in the presence of Cu(OAc) 2 48 in homogenous systems. However, despite these important contributions, more work still needs to be done to identify new heterogeneous systems for a highly effective catalyst.…”

Section: 39mentioning

confidence: 99%

Cu₂(BDC)₂(BPY)–MOF: an efficient and reusable heterogeneous catalyst for the aerobic Chan–Lam coupling prepared via ball-milling strategy

et al. 2017

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Nanoporous Cu 2 (BDC) 2 (BPY)-MOF was used as efficient and reusable heterogeneous catalyst to effect the aerobic cross-coupling of aromatic amines and phenyl boronic acid (Chan-Lam coupling). Ball-milling strategy was utilized for the first as a powerful green and energy-efficient method for the synthesis of this nanoporous metal-organic framework. Certain ratio of metal ion and organic linkers were held to improve the quality of nanostructures. Cu 2 (BDC) 2 (BPY) were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and BrunauerEmmett-Teller (BET) surface area analysis.

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Section: 39mentioning

confidence: 99%

Cu₂(BDC)₂(BPY)–MOF: an efficient and reusable heterogeneous catalyst for the aerobic Chan–Lam coupling prepared via ball-milling strategy

et al. 2017

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“…IV reacts with an aniline to give complex I and completes the metal catalytic cycle. This type of relay between photoredox catalysis and nickel catalysis has been exploited for C-C coupling 30,38,39 , and electron-transfer via photoredox catalysis is reported to promote C(sp 2 )-N reductive elimination 40,41 . However, a similar strategy has not been demonstrated for C(sp 3 )-N coupling.…”

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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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Abstract: Arylamines constitute the core structure of many therapeutic agents,a grochemicals,a nd organic materials.T he development of methods for the efficient and selective construction of these structural motifs from simple building blocks is desirable but still challenging.W ed emonstrate that protonated electron-poor O-aryl hydroxylamines give aminium radicals in the presence of Ru(bpy) 3 Cl 2 .T hese highly electrophilic species undergo polarized radical addition to aromatic compounds in high yield and selectivity.W es uccessfully applied this method to the late-stage modification of chiral catalyst templates,t herapeutic agents,and natural products.N,N-Dialkyl arylamines are ap rivileged scaffold found in blockbuster drugs,a grochemicals,a nd organic materials (Scheme 1A).[1] These molecular frameworks are usually assembled through Pd 0 -o rC u I/II -catalysed cross-couplings of amine nucleophiles and aryl halides (i.e., Ullmann [2] and Buchwald-Hartwig [3] coupling reactions) or arylboronic acids (i.e., Chan-Lam coupling [4] ).[5] However,t hese approaches require the use of sometimes expensive catalysts,f orcing reaction conditions,a nd pre-functionalized aromatics.T his latter aspect can be problematic when the aromatic partner is difficult to make or the introduction of halides or B functionalities suffers from directionality issues (ortho vs. meta vs. para). As such, methods for the direct amination of unfunctionalized aromatic compounds are very desirable but far from being general.

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confidence: 99%

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confidence: 99%

“…[1] These molecular frameworks are usually assembled through Pd 0 -o rC u I/II -catalysed cross-couplings of amine nucleophiles and aryl halides (i.e., Ullmann [2] and Buchwald-Hartwig [3] coupling reactions) or arylboronic acids (i.e., Chan-Lam coupling [4] ). [5] However,t hese approaches require the use of sometimes expensive catalysts,f orcing reaction conditions,a nd pre-functionalized aromatics.T his latter aspect can be problematic when the aromatic partner is difficult to make or the introduction of halides or B functionalities suffers from directionality issues (ortho vs. meta vs. para).…”

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Synthesis of Arylamines via Aminium Radicals

et al. 2017

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Arylamines constitute the core structure of many therapeutic agents,a grochemicals,a nd organic materials.T he development of methods for the efficient and selective construction of these structural motifs from simple building blocks is desirable but still challenging.W ed emonstrate that protonated electron-poor O-aryl hydroxylamines give aminium radicals in the presence of Ru(bpy) 3 Cl 2 .T hese highly electrophilic species undergo polarized radical addition to aromatic compounds in high yield and selectivity.W es uccessfully applied this method to the late-stage modification of chiral catalyst templates,t herapeutic agents,and natural products.N,N-Dialkyl arylamines are ap rivileged scaffold found in blockbuster drugs,a grochemicals,a nd organic materials (Scheme 1A).[1] These molecular frameworks are usually assembled through Pd 0 -o rC u I/II -catalysed cross-couplings of amine nucleophiles and aryl halides (i.e., Ullmann [2] and Buchwald-Hartwig [3] coupling reactions) or arylboronic acids (i.e., Chan-Lam coupling [4] ).[5] However,t hese approaches require the use of sometimes expensive catalysts,f orcing reaction conditions,a nd pre-functionalized aromatics.T his latter aspect can be problematic when the aromatic partner is difficult to make or the introduction of halides or B functionalities suffers from directionality issues (ortho vs. meta vs. para). As such, methods for the direct amination of unfunctionalized aromatic compounds are very desirable but far from being general. [6] Nitrogen radicals [7] are highly reactive species that are now witnessing aresurgence of synthetic interest owing to the ability of photoredox catalysis [8] to promote single-electron transfer (SET) [9] processes under mild conditions.[10] While highly electrophilic amidyl [11] and sulfamidyl radicals [12] have been successfully coupled with highly electron-rich aromatic compounds (e.g.,i ndole,p yrrole), the use of dialkyl-substituted nitrogen radicals (aminyl radicals) in related arylations has yet to be described. This lack of synthetic application can be explained by the intrinsic nucleophilic nature of aminyls, which causes repulsive interactions between their lone pair and the aromatic ring.[13] However,upon protonation, aminyl radicals are converted into aminium radicals [10d,i,14] that are isoelectronic to alkyl radicals but carry af ormal positive charge (Scheme 1B). This makes them powerful electrophiles that undergo highly polarized radical processes.I ndeed, pioneering work from Minisci and co-workers showed that N À Cl amines can be arylated upon photochemical N À Cl bond homolysis.[15] While successful, these reactions have not been employed in mainstream organic synthesis owing to three main limitations:1 )the aromatic compound is ac o-solvent (10-20 equiv);2 )high-energy light (l < 280 nm) is required and 3) the reactions are run in refluxing AcOH/H 2 SO 4 .[15c]We recently developed av isible-light-mediated synthesis of iminyl [16] and amidyl [11c] radicals through reductive SET fragmentation o...

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Visible‐Light‐Mediated Chan–Lam Coupling Reactions of Aryl Boronic Acids and Aniline Derivatives

Cited by 140 publications

References 52 publications

Cu₂(BDC)₂(BPY)–MOF: an efficient and reusable heterogeneous catalyst for the aerobic Chan–Lam coupling prepared via ball-milling strategy

Cu₂(BDC)₂(BPY)–MOF: an efficient and reusable heterogeneous catalyst for the aerobic Chan–Lam coupling prepared via ball-milling strategy

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

Synthesis of Arylamines via Aminium Radicals

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Visible‐Light‐Mediated Chan–Lam Coupling Reactions of Aryl Boronic Acids and Aniline Derivatives

Cited by 140 publications

References 52 publications

Cu2(BDC)2(BPY)–MOF: an efficient and reusable heterogeneous catalyst for the aerobic Chan–Lam coupling prepared via ball-milling strategy

Cu2(BDC)2(BPY)–MOF: an efficient and reusable heterogeneous catalyst for the aerobic Chan–Lam coupling prepared via ball-milling strategy

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

Synthesis of Arylamines via Aminium Radicals

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Product

Resources

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Cu₂(BDC)₂(BPY)–MOF: an efficient and reusable heterogeneous catalyst for the aerobic Chan–Lam coupling prepared via ball-milling strategy

Cu₂(BDC)₂(BPY)–MOF: an efficient and reusable heterogeneous catalyst for the aerobic Chan–Lam coupling prepared via ball-milling strategy