A Versatile Method for Suzuki Cross‐Coupling Reactions of Nitrogen Heterocycles

Kudo, Noriaki; Perseghini, M.; Fu, Gregory C.

doi:10.1002/ange.200503479

Cited by 125 publications

(63 citation statements)

References 13 publications

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“…It is therefore an attractive target to render palladium-phosphine complexes water-soluble in order to allow cross-coupling reactions in this "green" solvent. [87,88] Only a few examples of aqueous Suzuki coupling of aryl chlorides have been described, notable in this respect are recent publications by Buchwald et al [89,90] and Fu et al [11] who report on the facile Suzuki coupling in water and water/dioxane for a broad range of substrates. [4,[91][92][93] Consequently, to render the 9-fluorenylphos- www.chemeurj.org phines water soluble, the aromatic ring was sulfonated by treatment of the phosphonium salt 17 c with concentrated sulphuric acid, resulting in the formation of the respective 2-sulfonated fluorene in 77 % yield (Scheme 5).…”

Section: Resultsmentioning

confidence: 97%

“…[68,[96][97][98] Recently, Fu et al and Buchwald et al reported catalysts that are able to couple various substituted pyridylboronic acids and aryl chlorides in 90-95 % yield by using 2-3 mol % of Pd catalyst at 90-100 8C during 24 h in n-butanol or in dioxane/water as solvents. [11,68] Encouraged by the high activity of the Pd complexes of the sulfonated fluorenene 18, we also tried coupling reactions of pyridylboronic acid in the aqueous Suzuki coupling (Table 7, entries 24-28). Activated aryl chlorides (2-CF 3 -chlorobenzene, Table 7, entry 26) require only 0.1 mol % of catalyst at 100 8C for quantitative conversion, while nonactivated (chlorobenzene) aryl chlorides work with 0.5 mol % (entry 25).…”

Section: Resultsmentioning

confidence: 99%

“…Trialkylphosphines with bulky substituents are highly useful ligands for palladium-complex catalysts in various types of cross-coupling reactions of the Suzuki, [1][2][3][4][5][6][7][8][9][10][11] Sonogashira, [12][13][14][15][16][17][18][19][20][21] Heck, [22][23][24][25][26][27] Buchwald-Hartwig amination [28][29][30][31][32][33][34] and ether formation, [35] Negishi, [36] Stille, [37][38][39] Hiyama, [40] Kumada, [41] a-arylation, [42,43] and carbonylation type. [44] The main reasons for the favorable catalytic properties of trialkylphosphine-palladium complexes are the electron-richness and the steric bulk of trialkylphosphine ligands, which favor the formation of low-coordinate and highly active Pd complexes, possibly of the L 1 Pd type, [45][46]…”

Section: Introductionmentioning

confidence: 99%

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9‐Fluorenylphosphines for the Pd‐Catalyzed Sonogashira, Suzuki, and Buchwald–Hartwig Coupling Reactions in Organic Solvents and Water

Fleckenstein

Plenio

2007

Chemistry A European J

171

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The lithiation/alkylation of fluorene leads to various 9-alkyl-fluorenes (alkyl=Me, Et, iPr, -Pr, -C18H25) in>95% yields, for which lithiation and reaction with R2PCl (R=Cy, iPr, tBu) generates 9-alkyl, 9-PR2-fluorenes which constitute electron-rich and bulky phosphine ligands. The in-situ-formed palladium-phosphine complexes ([Na2PdCl4], phosphonium salt, base, substrates) were tested in the Sonogashira, Suzuki, and Buchwald-Hartwig reactions of aryl chlorides and aryl bromides in organic solvents. The Sonogashira coupling of aryl chlorides at 100-120 degrees C leads to>90% yields with 1 mol% of Pd catalyst. The Suzuki coupling of aryl chlorides typically requires 0.05 mol% of Pd catalyst at 100 degrees C in dioxane for quantitative product formation. To carry out "green" cross-coupling reactions in water, 9-ethylfluorenyldicyclohexylphosphine was reacted in sulphuric acid to generate the respective 2-sulfonated phosphonium salt. The Suzuki coupling of activated aryl chlorides by using this water-soluble catalyst requires only 0.01 mol% of Pd catalyst, while a wide range of aryl chlorides can be quantitatively converted into the respective coupling products by using 0.1-0.5 mol% of catalyst in pure water at 100 degrees C. Difficult substrate combinations, such as naphthylboronic acid or 3-pyridylboronic acid and aryl chlorides are coupled at 100 degrees C by using 0.1-0.5 mol% of catalyst in pure water to obtain the respective N-heterocycles in quantitative yields. The copper-free aqueous Sonogashira coupling of aryl bromides generates the respective tolane derivatives in>95% yield.

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

9‐Fluorenylphosphines for the Pd‐Catalyzed Sonogashira, Suzuki, and Buchwald–Hartwig Coupling Reactions in Organic Solvents and Water

Fleckenstein

Plenio

2007

Chemistry A European J

171

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“…The importance of these building blocks in medicinal chemistry and materials sciences [2] has prompted continued methodological efforts, and two very recent reports highlight the importance of this goal. [3,4] Absent from these and the predominance of reports are some of the most problematic organometallic reagents-azines bearing the metal adjacent to a nitrogen atom. The problem is even more severe with diazines (Scheme 1).…”

Section: Jean-philippe Leclerc and Keith Fagnou*mentioning

confidence: 97%

Palladium‐Catalyzed Cross‐Coupling Reactions of Diazine N‐Oxides with Aryl Chlorides, Bromides, and Iodides

2006

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“…[8,9] To ascertain that ligands (S)-1 a bind to two zinc(II) porphyrin building blocks (2), we measured the binding constants and performed a Job plot analysis. The UV/Vis titration experiment revealed binding constants of K 1 = 1.8 10 3 L mol À1 and K 2 = 1.7 10 3 L mol…”

mentioning

confidence: 99%

Supramolecular Control of Ligand Coordination and Implications in Hydroformylation Reactions

et al. 2011

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Coordination chemistry and organometallic chemistry have intensely fuelled the field of transition metal catalysis, and knowledge-based ligand design is, next to combinatorial and high-throughput experimentation, a leading approach to develop new catalytic systems. For the industrially important hydroformylation reaction, ligand effects have been studied in detail, also with the aid of high-pressure spectroscopy techniques, (for example, HP NMR and HP-IR).[1] The active species in this reaction is a trigonal bipyramidal complex, with a hydride on the axial position. The classical Wilkinsons dissociative mechanism, based on triphenyl phosphine as ligand, is widely accepted and explains most observations made to date. Two coordination complexes have been observed with either the ligands coordinated in the equatorial-equatorial (eq-eq) or in the equatorial-axial (eq-ax) mode (Scheme 1).Van Leeuwen et al. elegantly demonstrated that bidentate phosphorus ligands with wide bite angles predominantly lead to the formation of the eq-eq rhodium complex, resulting in highly selective rhodium-catalyzed hydroformylation of 1-octene, and promoting the formation of the linear aldehyde product.[2] In the field of asymmetric hydroformylation, the most promising class of ligands are hybrid phosphines and phosphites or phosphoroamidites.[3] A real breakthrough in this field was achieved by Takaya, Nozaki et al. with the discovery of Binaphos, which gives ee values of up to 95 % for a wide range of substrates.[4] The reason for the exceptionally high enantioselectivity is attributed to the exclusive formation of a single active species, in which the ligand coordinates in eq-ax mode to the transition-metal center. Monodentate ligands have been much less applied in these transformations, as lower selectivities are anticipated owing to lower control over coordination modes. However, because of their simple structure, their synthesis is generally much less elaborate, making these ligands potentially cheaper and enabling the preparation of large ligand libraries, which are required to rapidly find new active and selective catalysts by rapid screening technologies. Application of very bulky monodentate phosphite (p-accepting) ligands demonstrated that these form very active catalysts that are also active in the hydroformylation of internal alkenes, albeit with significant isomerization.[5] Spectroscopy experiments on such systems indicate that only one phosphite ligand coordinates to the metal center in the equatorial plane. Along the same lines, Breit et al. have reported the use of bulky phosphabenezenes in hydroformylation catalysis.[6] In situ high-pressure NMR investigations demonstrate the prevalent formation of a monophosphine rhodium complex in which the ligand is located in equatorial position whereas the hydride occupies the axial site, which accounts for the reported activity and selectivity.Recently, we have introduced a ligand-template approach for the supramolecular encapsulation of transition-metal complexes.[7] Ligand-temp...

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A Versatile Method for Suzuki Cross‐Coupling Reactions of Nitrogen Heterocycles

Cited by 125 publications

References 13 publications

9‐Fluorenylphosphines for the Pd‐Catalyzed Sonogashira, Suzuki, and Buchwald–Hartwig Coupling Reactions in Organic Solvents and Water

9‐Fluorenylphosphines for the Pd‐Catalyzed Sonogashira, Suzuki, and Buchwald–Hartwig Coupling Reactions in Organic Solvents and Water

Palladium‐Catalyzed Cross‐Coupling Reactions of Diazine N‐Oxides with Aryl Chlorides, Bromides, and Iodides

Supramolecular Control of Ligand Coordination and Implications in Hydroformylation Reactions

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