Regiocontrolled Ru-catalyzed addition of carboxylic acids to alkynes: practical protocols for the synthesis of vinyl estersWe thank Prof. Dr. M. T. Reetz for generous support and constant encouragement, and gratefully acknowledge the DFG, the FCI, and the BMBF for financial support.

Gooßen, Lukas J.; Paetzold, Jens; Koley, Debasis

doi:10.1039/b211277a

Cited by 154 publications

(67 citation statements)

References 17 publications

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“…[20,21] One of the most interesting reports showed that changing the ligand and base, with the same ruthenium catalyst, allowed access to either the anti-Markovnikov or Markovnikov products in excellent yield (Table 1). [22] To highlight the utility of this type of reaction, Dixneuf and coworkers have investigated a ruthenium-catalyzed isomerization process (Scheme 12). In this transformation, benzoic acid adds regioselectively to putative metal vinylidene complexes, and the resulting Z-enol esters then fragment at higher temperatures to give enal products in good yields.…”

Section: Carbamate Nucleophilesmentioning

confidence: 99%

Metal Vinylidenes as Catalytic Species in Organic Reactions

Trost

McClory

2008

Chemistry An Asian Journal

189

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Organic vinylidene species have found limited use in organic synthesis due to their inaccessibility. In contrast, metal vinylidenes are much more stable, and may be readily accessed through transition metal activation of terminal alkynes. These electrophilic species may be trapped by a number of nucleophiles. Additionally, metal vinylidenes can participate in pericyclic reactions and processes involving migration of a metal ligand to the vinylidene species. This review addresses the reactions and applications of metal vinylidenes in organic synthesis.

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Section: Carbamate Nucleophilesmentioning

confidence: 99%

Metal Vinylidenes as Catalytic Species in Organic Reactions

Trost

McClory

2008

Chemistry An Asian Journal

189

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“…Carboxylic acids react with propargylic alcohols in the presence of these catalytic systems, but lead to b-ketoesters rather than to hydroxy enol esters. [62,67,68] Recently, the catalytic addition of carboxylic acids to alkynes was revisited with other ruthenium catalyst systems, including [{RuCl 2 (p-cymene)} 2 ]/P(furyl) 3 /base, [69] [RuCl 2 (PCy 3 ) 2 CHtBu)]BF 4 , [70] and salicylaldimine-containing ruthenium complexes. [71][72][73] Attempts were made to reverse the addition regioselectivity of carboxylic acids to alkynes in order to produce 1-alkenyl esters, which are protected intermediates in the selective transformation of alkynes into aldehydes.…”

Section: Catalytic Addition Of Carboxylic Acids To Alkynes: a Convenimentioning

confidence: 99%

Metal Vinylidenes and Allenylidenes in Catalysis: Applications in Anti‐Markovnikov Additions to Terminal Alkynes and Alkene Metathesis

2006

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The involvement of a catalytic metal vinylidene species was proposed for the first time in 1986 to explain the regioselective formation of vinyl carbamates directly from terminal alkynes, carbon dioxide, and amines. Since this initial report, various metal vinylidenes and allenylidenes, which are key activation intermediates, have proved extremely useful for many alkyne transformations. They have contributed to the rational design of new catalytic reactions. This 20th anniversary is a suitable occasion to present the advancement of organometallic vinylidenes and allenylidenes in catalysis.

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“…[15,18] Moreover,i nt he presence of electron-deficient transition-metal catalysts or ruthenium(II), alkynes preferentially react with the nucleophilic carboxylate, to form enol esters,rather than with the CÀHmoiety. [19] This reactivity points to the challenges associated with developing selective C À Hh ydroarylations in the proximity of ar eactive carboxylate. [20] In continuation of our research on the use of carboxylic acids as substrates in transition-metal catalysis, [11, 12d, 17] we explored whether carboxylate groups could be utilized as directing groups in redox-neutral intermolecular hydroarylaScheme 1.…”

mentioning

confidence: 99%

“…However,t he simple ruthenium complex [Ru(pcym)Cl 2 ] 2 ,u sually an efficient hydroacyloxylation catalyst, [19] surprisingly furnished 3aa in an encouraging 48 %yield with ah igh 7:1r egioselectivity in favor of the methyl-branched stilbene derivative (entry 1). Thei odine-bridged analogue [Ru(p-cym)I 2 ] 2 proved to be an even more active and selective catalyst (entries 2a nd 3).…”

mentioning

confidence: 99%

Regioselective C−H Hydroarylation of Internal Alkynes with Arenecarboxylates: Carboxylates as Deciduous Directing Groups

et al. 2016

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In the presence of catalytic [Ru(p-cym)I 2 ] 2 and the base guanidine carbonate,b enzoica cids react with internal alkynes to give the corresponding 2-vinylbenzoic acids.T his alkyne hydroarylation is generally applicable to diversely substituted electron-rich and electron-poor benzoic and acrylic acids.A ryl(alkyl)acetylenes react regioselectively with formation of the alkyl-branched hydroarylation products,a nd propargylic alcohols are converted into g-alkylidene-d-lactones.T he hydroarylation can also be conducted decarboxylatively with ad ifferent choice of catalyst and reaction conditions.T his reaction variant, which does not proceed via intermediate formation of 2-vinylbenzoic acids,o pens up ar egioselective,w aste-minimized synthetic entry to vinylarenes.Given the prevalence of vinylarene moieties in functional materials,p harmaceuticals,a nd natural products, [1] efficient methods for the construction of this structural motif are constantly sought. Established synthetic approaches include Mizoroki-Heck [2] and Fujiwara-Moritani reactions, [3] as well as various catalytic cross-couplings of organometallic reagents with alkynes. [4] C À Hh ydroarylations of alkynes are advantageous over these processes,b ecause they require neither prefunctionalized substrates nor oxidants.S ince the pioneering studies by Murai and co-workers, [5] various metals have been found to efficiently catalyze the hydroarylation of alkynes,for example Ru, [6] Rh, [7] Re, [8] Co, [9] and others.[10] However, these CÀH functionalizations are highly regioselective only when directed by ketone,p yridine,a mide,s ulfoxide,o ro ther strong directing groups,groups which need to be synthesized in additional reaction steps and are not easily removed.Arguably,t he most advantageous directing groups in ortho-functionalizations are carboxylates,b ecause benzoic acids are widely available in great structural diversity and at low cost, and can subsequently be derivatized further, utilized as leaving groups in decarboxylative couplings, [11] or removed tracelessly by protodecarboxylation.[12] However,t he weak coordinating ability of this group poses additional challenges in the development of regiospecific CÀH-activating processes. In recent years,s ubstantial advances in carboxylate-directed CÀHa ctivation have been made, [13] for example,b yt he groups of Yu, [14] Miura, [15] Ackermann, [16] and Larrosa, [12b,c] as well as our own group. [12d, 17] In this context, oxidative couplings of benzoic acids with alkynes to form isocoumarins,naphthalenes,and other cyclic structures have intensively been studied. These reactions involve carboxylate-directed CÀHa ctivation to give vinylmetal intermediates,w hich immediately undergo cyclization steps before either reductive elimination or protonolysis can occur (Scheme 1a). [15,18] Moreover,i nt he presence of electron-deficient transition-metal catalysts or ruthenium(II), alkynes preferentially react with the nucleophilic carboxylate, to form enol esters,rather than with the CÀHmoiety...

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Regiocontrolled Ru-catalyzed addition of carboxylic acids to alkynes: practical protocols for the synthesis of vinyl estersWe thank Prof. Dr. M. T. Reetz for generous support and constant encouragement, and gratefully acknowledge the DFG, the FCI, and the BMBF for financial support.

Cited by 154 publications

References 17 publications

Metal Vinylidenes as Catalytic Species in Organic Reactions

Metal Vinylidenes as Catalytic Species in Organic Reactions

Metal Vinylidenes and Allenylidenes in Catalysis: Applications in Anti‐Markovnikov Additions to Terminal Alkynes and Alkene Metathesis

Regioselective C−H Hydroarylation of Internal Alkynes with Arenecarboxylates: Carboxylates as Deciduous Directing Groups

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