The synthesis of non‐symmetrical stilbene analogs of <i>trans</i>‐resveratrol using the same Pd catalyst in a sequential double‐Heck arylation of ethylene

Nobre, Sabrina Madruga; Muniz, Mauro Neves; Seferin, Marcus; Silva, Wagner; Monteiro, Adriano L.

doi:10.1002/aoc.1756

Cited by 13 publications

(8 citation statements)

References 42 publications

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“…24 A catalytic system consisting of Pd(OAc) 2 and P(o-tol) 3 became possible to carry out two consecutive Heck arylations without losing activity from the first to the second Heck reaction. This approach is also used in the present work to obtain a trisubstituted olefin from styrene in a one pot protocol (Scheme 4).…”

Section: Resultsmentioning

confidence: 99%

Pd-catalyzed Heck reactions of aryl bromides with 1,2-diarylethenes

Limberger¹,

Poersch²,

Monteiro³

2011

J. Braz. Chem. Soc.

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Um sistema catalítico composto por Pd(OAc) 2 e P(o-tol) 3 foi aplicado na reação de Heck entre brometos de arila e diariletenos. Utilizando-se K 2 CO 3 como base e DMF como solvente, olefinas triarilsubstituídas foram obtidas com rendimentos de bons a excelentes. Brometos de arila com substituintes eletroretiradores foram menos ativos para a reação de acoplamento Heck e levaram à formação de produto de homoacoplamento em quantidades substanciais, indicando que a adição oxidativa não deve ser a etapa lenta da reação. A presença de substituintes no diarileteno afetou drasticamente a seletividade da reação. Realizou-se também a dupla arilação do estireno, levando diretamente à olefina triarilsubstituída, com rendimento de 73%.A catalytic system composed of Pd(OAc) 2 and P(o-tol) 3 was found to be effective for the Heck reaction of aryl bromides with diarylethylenes. Using K 2 CO 3 as a base and DMF as a solvent, trisubstituted olefins were obtained in good to excellent yields. Aryl bromides containing an electron-withdrawing group in para position were less reactive for the Heck coupling reaction and gave substantial amount of homocoupling by-product suggesting that oxidative addition is not the rate-determining step. Electron withdrawing group substituent in the para position of stilbene affects the regioselectivity of the reaction. In this case, the phenyl group from the Ph-Pd complex migrates preferentially to the same carbon of the double bond to which the phenyl is bonded. Finally, a one pot sequential double Heck arylation of styrene was performed, giving trisubstituted olefin with an overall yield of 73%.Keywords: Heck reaction, palladium, trisubstituted olefins, double arylation IntroductionPalladium-catalyzed Heck cross-coupling reactions are one of the most efficient methods for the construction of C−C bonds and have found widespread use in organic synthesis.1 Most Heck reactions involves arylation of monosubstituted alkenes (especially acrylates and styrene derivatives) to allow synthesis of disubstituted olefins with regio and stereoselective control. In contrast, fewer studies have been conducted on the arylation of disubstituted olefins or double arylation of mono-substituted olefins, to yield trisubstituted products. Stereocontrol during the synthesis of highly substituted double bonds is a significant challenge in organic synthesis, 2 and the Heck reaction remains an important alternative. In this context, some examples of regio and stereoselective syntheses of trisubstituted α,β-unsaturated compounds, such as nitriles, 3,4 cinnamates 5-10 and aldehydes, 11 through either monoarylation of disubstituted olefins or direct diarylation of monosubstituted olefins, have been reported. Arylation of disubstituted alkenes without an electron-withdrawing group conjugated to the C=C double bond (e.g., α-or β-methylstyrene, 10,12 1,1-diphenylethene and transstilbene)13-15 has also been investigated. However, to the best of our knowledge, no example using substituted stilbenes has been described. Recently, we re...

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Section: Resultsmentioning

confidence: 99%

Pd-catalyzed Heck reactions of aryl bromides with 1,2-diarylethenes

Limberger¹,

Poersch²,

Monteiro³

2011

J. Braz. Chem. Soc.

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“…Notably, palladium‐catalyzed Heck coupling4 between an olefin4a and aryl halide (or its surrogates)4b,c has garnered significant attention for generating numerous biologically active stilbenoids like resveratrol,4d pterostilbene,4e etc. However, one of the coupling partners, that is, styrene, is inevitably prone to polymerization, difficult to synthesize, and tricky to purify.…”

Section: Methodsmentioning

confidence: 99%

Tandem Heck/Decarboxylation/Heck Strategy: Protecting‐Group‐Free Synthesis of Symmetric and Unsymmetric Hydroxylated Stilbenoids

et al. 2012

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“…[1][2][3][4] Particularly, the controlled insertion of aryl and aryloxy fragments into olen scaffolds is an important task for the synthesis of bioactive compounds, such as Z-tamoxifene, 2,5-7 sertraline, 8 indatraline, 8 and tolterodine, 9 among others. [10][11][12] 1,1-Diaryl trisubstituted alkenes, specically, are usually synthesised by mono or di Heck arylation of cinnamates, [13][14][15][16] a,b-unsaturated adehydes 17 and acrylonitriles. 18,19 However, these methodologies contain some drawbacks.…”

Section: Introductionmentioning

confidence: 99%