Synthesis of Fused Carbocycles via a Selective 6-<i>Endo</i> Dig Gold(I)-Catalyzed Carbocyclization

Barabé, Francis; Levesque, Patrick; Korobkov, Ilia; Barriault, Louis

doi:10.1021/ol202314q

Cited by 90 publications

(48 citation statements)

References 36 publications

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“…(21, 22) Lately, these ligands have been borrowed in gold catalysis with much success,(23–30) but modification of them for gold catalysis is rare. (31) Perhaps due to the nature of Pd catalysis, the lower half of the bottom phenyl ring of these ligands (i.e., C3’, C4’ and C5’) has seldom been substituted with functional groups.…”

Section: Resultsmentioning

confidence: 99%

A general ligand design for gold catalysis allowing ligand-directed anti-nucleophilic attack of alkynes

Wang

et al. 2014

Nat Commun

142

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Most homogenous gold catalyses demand ≥0.5 mol % catalyst loading. Due to the high cost of gold, these reactions are unlikely to be applicable in medium or large scale applications. Here we disclose a novel ligand design based on the privileged biphenyl-2-phosphine framework that offers a potentially general approach to dramatically lowering catalyst loading. In this design, an amide group at the 3’ position of the ligand framework directs and promotes nucleophilic attack at the ligand gold complex-activated alkyne, which is unprecedented in homogeneous gold catalysis considering the spatial challenge of using ligand to reach antiapproaching nucleophile in a linear P-Au-alkyne centroid structure. With such a ligand, the gold(I) complex becomes highly efficient in catalyzing acid addition to alkynes, with a turnover number up to 99,000. Density functional theory calculations support the role of the amide moiety in directing the attack of carboxylic acid via hydrogen bonding.

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Section: Resultsmentioning

confidence: 99%

A general ligand design for gold catalysis allowing ligand-directed anti-nucleophilic attack of alkynes

Wang

et al. 2014

Nat Commun

142

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“…[18] Furthermore,t he Thorpe-Ingold effect was found to be important for the success of the cyclization. [19] Whereas the current conditions can only be applied for the formation of five-membered rings,a fter extensive investigation, ar uthenium-based system was discovered that enables 6-exo-trig cyclizations with both cyclic and acyclic ketones (Scheme 1a,b). (1)].…”

Section: Methodsmentioning

confidence: 99%

Catalytic Intramolecular Ketone Alkylation with Olefins by Dual Activation

Lim

Dong

2015

Angewandte Chemie

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Tw oc omplementary methods for catalytic intramolecular ketone alkylation reactions with unactivated olefins, resulting in Conia-ene-type reactions,a re reported. The transformations are enabled by dual activation of both the ketone and the olefin and are atom-economical as stoichiometric oxidants or reductants are not required. Assisted by Kools aniline catalyst, the reaction conditions can be both pH-and redox-neutral. Ab road range of functional groups are thus tolerated. Whereas the rhodium catalysts are effective for the formation of five-membered rings,aruthenium-based system that affords the six-membered ring products was also developed.Intramolecular ketone-olefin/alkyne couplings,n amely the Conia-ene reaction, [1] represent ap owerful strategy for constructing ring systems through CÀCb ond formation, particularly owing to the orthogonal reactivity of carbonyl and alkenyl/alkynyl groups.W ith the advancement of p-acid catalysis,anumber of elegant approaches have been developed for alkyne-mediated couplings,p articularly those involving 1,3-dicarbonyl compounds. [2][3][4][5] In contrast, few cyclization reactions of an unactivated alkene and ar egular ketone are known, which is likely due to the reduced coordination ability of olefins (compared to alkynes) and ap oor enol/ketone ratio with normal ketones.T he thermal Conia-ene reaction typically requires very high temperatures (300-400 8 8C), which limits the substrate scope and functionalgroup tolerance.[1] To the best of our knowledge,o nly two catalytic Conia-ene-type reactions involving simple ketone/ olefin substrates have been reported to date ( Figure 1B). Widenhoefer [6] and co-workers first developed ap alladiumcatalyzed 6-endo-trig cyclization of g,d-enones for cyclohexanone synthesis;C he [7] et al. recently described ag oldcatalyzed intramolecular hydroalkylation of ketones with aliphatic mono-and 1,1-disubstituted alkenes.While efficient, both methods require strong Brønsted or Lewis acids for ketone enolization, which potentially leads to incompatibility with acid-sensitive functional groups.F urthermore,C oniaene-type cyclizations of aryl-substituted olefins have not been reported to date.To develop ab roadly applicable intramolecular ketoneolefin coupling that avoids extreme temperatures or strongly acidic conditions,analternative approach was sought without relying on ketone enolization. Herein, efforts toward developing ac atalytic Conia-ene-type reaction by dual activation of the ketone and olefin are described. This approach is expected to operate under nearly pH-neutral conditions without stoichiometric oxidant or reductant, and should thus be applicable to ab road substrate scope and benefit from good functional-group compatibility.Recently,w er eported an intermolecular ketone a-alkylation reaction by coupling with simple olefins using abifunctional ligand (7-azaindoline) that is capable of forming an enamine with the ketone and then directs Rh insertion into the vinyl CÀHb ond.[8] Thea lkylation shows complete regioselect...

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“…Owing to the high affinity of gold(I) complexes to C–C π-systems in the presence of other functional groups combined by its predictable reactivity pattern, the gold(I)-catalyzed reaction provides tremendous opportunities for the discovery of new and useful reactions [12]. Recently, we [13] and other groups [14–17] reported that divergent pathway can be obtained by modulating the steric and electronic properties of the gold(I) catalyst (Scheme 1). The ancillary ligand plays a direct role in the regioselectivity for the first bond formation rather than via a common intermediate created after an initial bond formation [18].…”

Section: Introductionmentioning

confidence: 99%

Gold(I)-catalyzed domino cyclization for the synthesis of polyaromatic heterocycles

Morin¹,

Levesque²,

Barriault³

2013

Beilstein J. Org. Chem.

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Synthesis of Fused Carbocycles via a Selective 6-Endo Dig Gold(I)-Catalyzed Carbocyclization

Cited by 90 publications

References 36 publications

A general ligand design for gold catalysis allowing ligand-directed anti-nucleophilic attack of alkynes

A general ligand design for gold catalysis allowing ligand-directed anti-nucleophilic attack of alkynes

Catalytic Intramolecular Ketone Alkylation with Olefins by Dual Activation

Gold(I)-catalyzed domino cyclization for the synthesis of polyaromatic heterocycles

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