The Heck Reaction as a Sharpening Stone of Palladium Catalysis

Beletskaya, I. P.; Cheprakov, Andrei V.

doi:10.1021/cr9903048

Cited by 3,766 publications

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“…A variety of unsaturated ligands undergo migratory insertion, including carbon monoxide, carbon dioxide, alkenes, alkynes, ketones, aldehydes, and imines, and migratory insertion is a common step in numerous catalytic reactions, including hydroformylation, [1,2] hydrogenation, [3][4][5] polymerization, [6][7][8][9] hydroarylation, [10][11][12][13][14] difunctionalization of alkenes, [15][16][17][18] and the olefination of aryl halides (commonly termed the Mizoroki-Heck reaction). [19][20][21][22] In most cases, the unsaturated ligand inserts into a metalcarbon (M À C) or metal-hydrogen (M À H) bond. Related insertions of alkenes into metal-oxygen (M À O) and metalnitrogen (MÀN) bonds are much less common (Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

Iridium-Catalyzed, Intermolecular Hydroetherification of Unactivated Aliphatic Alkenes with Phenols

Sevov

Hartwig

2013

J. Am. Chem. Soc.

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Metal-catalyzed addition of an O−H bond to an alkene is a desirable process because it allows for rapid access to ethers from abundant starting materials without the formation of waste, without rearrangements, and with the possibility to control the stereoselectivity. We report the intermolecular, metal-catalyzed addition of phenols to unactivated α-olefins. Mechanistic studies of this rare catalytic reaction revealed a dynamic mixture of resting states that undergo O−H bond oxidative addition and subsequent olefin insertion to form ether products.

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Section: Introductionmentioning

confidence: 99%

Iridium-Catalyzed, Intermolecular Hydroetherification of Unactivated Aliphatic Alkenes with Phenols

Sevov

Hartwig

2013

J. Am. Chem. Soc.

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“…Após 9 h de aquecimento a 100 °C, o produto desejado foi obtido em apenas 19% de rendimento e 49% de ee. Esta reação é análoga à reação de Heck-Mizoroki, 61 com a diferença de que ao invés da inserção do paládio em uma ligação C-X (X = OTf, halogênio, etc), o que precede a formação do intermediário σ-arilpaládio é uma ativação C(sp 2 )-H.…”

Section: Fronteira: O Constante Desafio Do Passo à Frenteunclassified

O desafio da ativação das ligações C-H em síntese orgânica

Correia¹

2011

Quím. Nova

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Recebido em 11/3/11; aceito em 9/6/11; publicado na web em 9/8/11 THE CHALLENGE OF C-H ACTIVATION IN ORGANIC SYNTHESIS. This review aims at to the presentation and discussion of the principal aspects of the C-H activation by transition metals. Representative examples were selected from the recent literature to illustrate these principles beginning with somewhat simple examples and moving up to more complex ones. The synthetic potential of the C-H activation, as well as the potential advantages and disadvantages of the methodology are highlighted with relevant recent examples, along with brief insights on the mechanism aspects of these reactions.Keywords: C-H activation; transition metals; organic synthesis.Em linhas gerais, para que uma reação orgânica aconteça é preciso que haja uma ligação química suscetível, de forma geral, à clivagem, migração, substituição e/ou adição. Naturalmente, tal ocorrência é induzida por um agente externo, seja ele uma molécula, uma fonte de energia, ou até mesmo outra parte da mesma molécula. Frequentemente, a ligação química em questão é relativamente ativada, isto é, possui patamar energético relativamente elevado, o que facilita sua manipulação sintética. Logo, é desejável que os substratos envolvidos em uma reação sejam previamente funcionalizados, ou seja, contenham sítios reacionais cuja natureza seja suscetível às condições do meio reacional.Frequentemente, utiliza-se o termo "ativação" para designar o aumento da reatividade de uma ligação/molécula frente a algum reagente ou condição reacional. Em muitos casos, o termo "ativação" implica na ruptura da ligação química. O principal resultado da ativação de uma ligação C-H é a sua substituição por uma ligação mais fraca/mais funcionalizada (i.e., mais suscetível a outras reações). Por exemplo, um composto insaturado pode ser ativado mediante coordenação a um centro metálico dos seus orbitais π. Entretanto, para um composto saturado esta rota não é possível e outros mecanismos devem ser utilizados. 1 Sobre as ligações C-H e a sua ativação, três informações básicas precisam ser previamente fornecidas: a ligação carbono-hidrogênio é uma das mais estáveis que existem, isto é, é termodinamicamente estável e cineticamente inerte; é uma ligação onipresente em compostos orgânicos; o maior estoque de moléculas orgânicas são as reservas de petróleo e gás natural, ou seja, a vasta maioria das matérias-primas da química são hidrocarbonetos. Logo, a ativação da ligação carbonohidrogênio (ativação C-H) não é nova. 1 Pelo contrário, a humanidade ainda estaria nos primórdios da evolução tecnológica caso não houvessem desenvolvimentos nesta área.O aproveitamento mais direto dos hidrocarbonetos, particularmente dos alcanos, é proporcionado pelo oxigênio, pois estes sofrem, a temperaturas devidas, oxidação completa, ou queima, fornecendo água, dióxido de carbono e muito calor. No entanto, à temperatura ambiente, sem a presença de um catalisador, os alcanos são praticamente inertes ao oxigênio atmosférico. Esta dicotomia, relacionada aos alcanos, ...

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“…For instance, using deactivated 4-bromoanisole as substrate led to quantitative (97%) product formation within 4.5 h in the presence of only 0.005 mol% of 2. Quantitative product formation but a further decrease in the conversion rates accompanied by low selectivity was observed after 5 h with 0.005 mol% of 2 with the electronically deactivated n-butyl vinyl ether ( Table 2, entries [17][18]. Even the sterically hindered 2-bromo-m-xylene was converted to 72% of product after only 8 h ( Furthermore, the exceptional high catalytic activity of 2 and its practical applicability was demonstrated in an exemplary 'large-scale' reaction, in which bromobenzene (210 ml; 2.0 mol) and styrene (250 ml; 2.4 mol) were quantitatively coupled in the presence of only 0.00002 mol% of catalyst within 36 h ( Table 2, entry 3).…”

Section: Heck Reactionmentioning

confidence: 99%

“…[4a,d] Nowadays, pincer complexes are in most cases considered as depot forms of palladium nanoparticles, but nevertheless, the involvement of Pd IV intermediates in the catalytic cycle still cannot be excluded completely. [18,19] Either way, the choice of aminophosphine pincer ligands might prove to be an advantage: Apart from their high σ-donor strength, aminophosphine ligands can donate additional electron density via the nitrogen lone pairs to the metal center, thereby making Pd IV intermediates more easily accessible. On the other hand, if palladium nanoparticles are the active species, pincer complexes should act as clean sources of palladium nanoparticles.…”

Section: Introductionmentioning

confidence: 99%

Aminophosphine Palladium Pincer Complexes for Suzuki and Heck Reactions

Bolliger¹,

Frech²

2009

Chimia

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The aminophosphine-based pincer complexes [C6H3-2,6-{NHP(piperidinyl)2}2Pd(Cl)] (2) and [C6H3-2,6-{OP(piperidinyl)2}2Pd(Cl)] (3) are readily prepared from cheap starting materials by sequential addition of 1,1′,1″-phosphinetriyltripiperidine and 1,3-diaminobenzene or resorcinol to solutions of [Pd(cod)(Cl)2] (cod = cyclooctadiene) in toluene under N2 in 'one pot'. Compounds 2 and 3 proved to be not only excellent catalysts for the Suzuki and the Heck cross-coupling reactions, but they are also very convenient to use: The toluene solutions of the 'one-pot' syntheses can be used directly for the catalytic reactions, thereby saving the time-consuming isolation of the catalysts. The Suzuki cross-coupling reaction catalyzed by 2 and 3 can be performed in air at 100 °C in toluene of technical quality: in the presence of only 0.001mol% of catalyst, several electronically deactivated and sterically hindered aryl bromides are quantitatively coupled with phenylboronic acid within a few minutes of reaction time. Furthermore, complex 2 enables the use of activated and non-activated aryl chlorides as coupling partners in the Suzuki reaction. Compounds 2 and 3 have also been shown to be highly active and reliable Heck catalysts: Very low catalyst loadings and short reaction times are required for the quantitative coupling of several electronically deactivated and sterically hindered aryl bromides with various olefins at 140 °C. At increased temperatures, even electronically deactivated and sterically hindered aryl chlorides can be efficiently coupled with olefins in the presence of only 0.01 mol% of catalyst. (3) are readily prepared from cheap starting materials by sequential addition of 1,1',1''-phosphinetriyltripiperidine and 1,3-diaminobenzene or resorcinol to solutions of [Pd(cod)(Cl) 2 ] (cod = cyclooctadiene) in toluene under N 2 in 'one pot'. Compounds 2 and 3 proved to be not only excellent catalysts for the Suzuki and the Heck cross-coupling reactions, but they are also very convenient to use: The toluene solutions of the 'one-pot' syntheses can be used directly for the catalytic reactions, thereby saving the time-consuming isolation of the catalysts. The Suzuki cross-coupling reaction catalyzed by 2 and 3 can be performed in air at 100 °C in toluene of technical quality: in the presence of only 0.001mol% of catalyst, several electronically deactivated and sterically hindered aryl bromides are quantitatively coupled with phenylboronic acid within a few minutes of reaction time. Furthermore, complex 2 enables the use of activated and non-activated aryl chlorides as coupling partners in the Suzuki reaction. Compounds 2 and 3 have also been shown to be highly active and reliable Heck catalysts: Very low catalyst loadings and short reaction times are required for the quantitative coupling of several electronically deactivated and sterically hindered aryl bromides with various olefins at 140 °C. At increased temperatures, even electronically deactivated and sterically hindered aryl chlorides can be efficiently c...

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The Heck Reaction as a Sharpening Stone of Palladium Catalysis

Cited by 3,766 publications

References 401 publications

Iridium-Catalyzed, Intermolecular Hydroetherification of Unactivated Aliphatic Alkenes with Phenols

Iridium-Catalyzed, Intermolecular Hydroetherification of Unactivated Aliphatic Alkenes with Phenols

O desafio da ativação das ligações C-H em síntese orgânica

Aminophosphine Palladium Pincer Complexes for Suzuki and Heck Reactions

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