Weakly Coordinating Directing Groups for Ruthenium(II)‐ Catalyzed CH Activation

Sarkar, Suman De; Liu, Weiping; Kozhushkov, Sergei I.; Ackermann, Lutz

doi:10.1002/adsc.201400110

Cited by 732 publications

(163 citation statements)

References 156 publications

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“…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.…”

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

et al. 2016

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“…Subsequently, the metallacycle 5 carbomanganates the a,b-unsaturated ester 2 by regioselective migratory insertion of the latter into the Mn À C bond. Through the assistance of the weakly coordinating [16,17] alkyloxycarbonyl group manganese enolate 6 is generated, which thereafter undergoes an intramolecular nucleophilic attack at the carbon atom of the imine moiety, thereby affording complex 7. The chelation of the imino group and the ester enolate motif by the manganese ion is suggested to facilitate this key cyclization, which in turn leads to the exclusive cis diastereoselectivity.…”

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Manganese‐Catalyzed Synthesis of cis‐β‐Amino Acid Esters through Organometallic CH Activation of Ketimines

et al. 2015

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“…8 To probe the mechanism of the C-H activation-annulation, we prepared d 5 -1a for the control experiments. First, we measured the value of K H/D = 3.17, indicating that C-H bond cleavage is the rate-determining step [Scheme 2, (1)].…”

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confidence: 99%

Sulfone promoted Rh(iii)-catalyzed C–H activation and base assisted 1,5-H shift strategy for the construction of seven-membered rings

2015

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Weakly Coordinating Directing Groups for Ruthenium(II)‐ Catalyzed CH Activation

Cited by 732 publications

References 156 publications

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

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

Manganese‐Catalyzed Synthesis of cis‐β‐Amino Acid Esters through Organometallic CH Activation of Ketimines

Sulfone promoted Rh(iii)-catalyzed C–H activation and base assisted 1,5-H shift strategy for the construction of seven-membered rings

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