Convenient Synthesis of 1H‐Indol‐1‐yl Boronates via Palladium(0)‐Catalyzed Borylation of Bromo‐1H‐indoles with ‘Pinacolborane’

Stadlwieser, Josef; Dambaur, Markus E.

doi:10.1002/hlca.200690097

Cited by 19 publications

(12 citation statements)

References 39 publications

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“…[2] Als Liganden für Gold, [3][4][5][6][7][8][9][10][11] Silber, [12] Rhodium, [13,14] Ruthenium [15][16][17] und Kupfer [18] verbesserten diese Phosphane die Reaktivität und Katalysatorstabilität. Die weitaus größte Bedeutung hatten sie aber für palladiumkatalysierte Reaktionen wie die Sonogashira-, [19] Negishi-, [20] Hiyama-, [21][22][23] Kumada- [24] und Suzuki-Kreuzkupplung [25][26][27][28][29][30] , die Heck-Reaktion, [31][32][33] die Enolatarylierung [34][35][36][37] und -allylierung, [38] die reduktive Cyclisierung [39] und Veretherung, [40][41][42][43] die Silylierung, [44] Borylierung, [45][46][47] Cyanierung, [48,49] Methylierung,…”

Section: Einführungunclassified

Biarylphosphanliganden in der palladiumkatalysierten Aminierung

2008

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In den vergangenen 12 Jahren erfuhr die palladiumkatalysierte Aminierung von Arylhalogeniden eine rasche Entwicklung, die durch die Einführung neuer Ligandenklassen vorangetrieben wurde. Biarylphosphane liefern in diesem Zusammenhang besonders reaktive Katalysatoren. Dieser Aufsatz behandelt Anwendungen solcher Katalysatoren zur C‐N‐Kreuzkupplung in der Synthese von Heterocyclen und Pharmazeutika, in den Materialwissenschaften und in der Naturstoffsynthese.

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Section: Einführungunclassified

Biarylphosphanliganden in der palladiumkatalysierten Aminierung

2008

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“…[2] These phosphines have been used as ligands for gold, [3][4][5][6][7][8][9][10][11] silver, [12] rhodium, [13,14] ruthenium [15][16][17] and copper [18] where they have been shown to impart improvements in reactivity and catalyst stability. It is in reactions catalyzed by palladium, however, that they have had by far the greatest impact including the Sonogashira, [19] Negishi, [20] Hiyama, [21][22][23] Kumada [24] and Suzuki [25][26][27][28][29][30] cross-coupling reactions, Heck reaction, [31][32][33] enolate arylation [34][35][36][37] and allylation, [38] reductive cyclization [39] and etherification, [40][41][42][43] silylation, [44] borylation, [45][46][47] cyanation, [48,…”

Section: Introductionmentioning

confidence: 99%

Biaryl Phosphane Ligands in Palladium‐Catalyzed Amination

2008

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Palladium-catalyzed amination of aryl halides has undergone rapid development in the last 12 years. This has been largely driven by implementation of new classes of ligands. Biaryl phosphines have proven to provide especially active catalysts in this context. This review discusses the applications that these catalysts have found in C-N cross-coupling in heterocycle synthesis, pharmaceuticals, materials science and natural product synthesis.

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“…8 In several cases, the C2/C3 regioselectivity of these functionalizations could be controlled by the reaction conditions or using directing groups. 4,9 Despite the important applications of acetylenes in synthetic chemistry, biochemistry, and material sciences, 10 there are only a few methods for the direct alkynylation of the indole core. 11 In 2009, Gu and Wang first introduced the C3-selective alkynylation of indoles using bromoacetylenes and a Pd catalyst.…”

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C2-Selective Direct Alkynylation of Indoles

et al. 2012

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The first C2-selective alkynylation of indoles using the hypervalent iodine reagent triisopropylsilylethynyl-1,2-benziodoxol-3(1H)-one (TIPS-EBX) with Pd(II) as a catalyst is described. This convenient and robust method gives a single-step access to substituted alkynyl indoles with very high C2 selectivity. The reaction is orthogonal to classical Pd(0) cross-coupling reactions as it is tolerant to bromide and iodide substituents. The used silyl protecting group can be easily removed to give terminal acetylenes.Since the first synthesis of indole by Baeyer almost 150 years ago, 1 interest in the preparation and functionalization of this privileged heterocycle has constantly grown.2 Indoles can indeed be found in numerous important molecules such as pharmaceuticals, dyes and natural products. Consequently, methods to synthesize and modify this heterocycle are of utmost importance in organic chemistry. † New Address: Institut für Organische Chemie und Biochemie, Albert-Ludwigs-Universität, Freiburg, Germany.(1 This document is the Accepted Manuscript version of a Published Work that appeared in final form in Organic Letters, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/doi/full/10.1021/ol3031389 groups among others. 8 In several cases, the C2/C3 regioselectivity of these functionalizations could be controlled by the reaction conditions or using directing groups. 4,9 Despite the important applications of acetylenes in synthetic chemistry, biochemistry, and material sciences, 10 there are only a few methods for the direct alkynylation of the indole core.11 In 2009, Gu and Wang first introduced the C3-selective alkynylation of indoles using bromoacetylenes and a Pd catalyst.11a C2-selective alkynylation is especially challenging and only two examples have been reported so far. Li and co-workers described an oxidative Heck-Cassar-Sonogashira type method for the alkynylation of 1,3-dimethylindole.11f This reaction could be applied to a broad scope of acetylenes, but only 3-methylindoles were reported. More recently, a method for the alkynylation of lithiated indoles using ethynylsulfonates as reagents was reported by Garcia Ruano and co-workers.11g,h Depending of the sterical hinderance of the substituent on the indole nitrogen, C2 or C3 alkynylation could be obtained. Nevertheless, the requirement for a strong base such as butyl lithium limited the scope of this transformation. Consequently, the most frequently used methods to access 2-alkynylated indoles are often based on the formation of the heterocycles via cyclisation reactions. 3(1H)-one (TIPS-EBX, 2)13 as an efficient reagent for the gold-catalyzed C3 alkynylation of indoles (Scheme 1). During our first investigation, palladium catalysts gave only traces of product, albeit with very high C2 selectivity. 11b We later demonstrated that efficient acetylene transfer with Pd catalysts was possible for the amino-and oxy-alkynylation o...

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Convenient Synthesis of 1H‐Indol‐1‐yl Boronates via Palladium(0)‐Catalyzed Borylation of Bromo‐1H‐indoles with ‘Pinacolborane’

Cited by 19 publications

References 39 publications

Biarylphosphanliganden in der palladiumkatalysierten Aminierung

Biarylphosphanliganden in der palladiumkatalysierten Aminierung

Biaryl Phosphane Ligands in Palladium‐Catalyzed Amination

C2-Selective Direct Alkynylation of Indoles

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