Palladium-Catalyzed Hydrophenylation of Alkynes with Sodium Tetraphenylborate under Mild Conditions

Zeng, Hanxiang; Hua, Ruimao

doi:10.1021/jo7020554

Cited by 61 publications

(27 citation statements)

References 30 publications

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“…[13] The stereochemical outcome of the reaction, as in the case of the Rh-catalyzed process, allowed sequential cyclization to occur. [14] The regioselectivity of the addition to unsymmetrical disubstituted alkynes was found to be influenced by steric factors and by the coordination with neighbouring groups (OH or 2-pyridyl); [13] the presence of an EWG substituent such as a keto [14b] or ester [15] group in the starting alkyne resulted in a selective b-arylation respect to the carbonyl group, but when the other substituent was a bulky tertiary alcoholic group both regioisomers were formed. A variety of ligand/solvent combinations was used in this case to direct the reaction towards the formation of one of the two regioisomers.…”

Section: Introductionmentioning

confidence: 99%

Rhodium‐ and Palladium‐Catalyzed Hydroarylation of Propargylic Amines with Arylboronic Acids

et al. 2010

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The hydroarylation of 3-arylprop-2-yn-1-amine derivatives with arylboronic acids has been studied in the presence of rhodium or palladium catalysts. By using a rhodium-based catalytic system, b,g-diarylallylamines were isolated in good yields. By contrast, the formation of the regiosomeric g,g-diar-A C H T U N G T R E N N U N G ylallylamines was achieved by means of a palladium catalyst in the presence of acetic acid. The complementary regioselectivity displayed by these two processes is a consequence of different catalytic cycles, involving respectively carborhodation or hydropalladation of the coordinated alkyne as key steps. Calculated charge distributions in the p-complexes are in accord with the results obtained.

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Section: Introductionmentioning

confidence: 99%

Rhodium‐ and Palladium‐Catalyzed Hydroarylation of Propargylic Amines with Arylboronic Acids

et al. 2010

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“…(v) The monoarene (Ar‐H) addition products were obtained exclusively under the conditions shown in Scheme . A similar method was reported for the preparation of monoarylated addition product for non‐phosphorylated alkynes but by using NaBPh 4 in place of phenylboronic acid 13…”

Section: Resultsmentioning

confidence: 99%

Efficient Palladium‐Catalyzed Double Arylation of Phosphonoalkynes and Diarylalkynes in Water: Use of a Dinuclear Palladium(I) Catalyst

2010

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“…1 H NMR spectra (400 MHz) were referenced to the residual protons of the deuterated solvent used. 13 C NMR spectra (101 MHz) were referenced internally to the D-coupled 13 C resonances of the NMR solvent. Chemical shifts (δ) are given in ppm, relative to deuterated solvent residual peak, and coupling constants (J) are provided in Hz.…”

Section: General Experimental Notesmentioning

confidence: 99%

A Highly Reduced Ni–Li–Olefin Complex for Catalytic Kumada–Corriu Cross-Couplings

et al. 2018

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As shown by the X-ray data, in the crystal structure complex 1 has a distorted trigonal bypyramidal geometry. However, variable temperature NMR studies revealed a fluxional behavior in solution (Scheme S2). Scheme S2 When the temperature is increased from-40 °C to 25 °C, the signals for the olefins reach a coalescence point and appear as one broad signal at 1.84 ppm. Importantly, when the same sample is then cooled down beyond the coalescence point (back to −40 °C), the characteristic signals for 1 observed at low temperature appear again. These results are in agreement with those reported by Jonas et al. (Angew. Chem. Int. Ed. 1980, 19, 520) which suggest a fluxional behavior of the ligands. A putative mechanism is depicted in Scheme S3. Scheme S3 S7 Oxidation state of the Nickel center: The structure of complex 1 contains 3 largely elongated olefins bound to the Ni center with distances of 1.42, 1.46 and 1.47 Å. This experimental observation is in agreement to the Dewar-Chatt-Duncanson model, in which the olefins can be described by the continuum from metallacyclopropane to olefin. Additionally, the Ni center is sharing electrons with the Li atom, thus making two metallic Ni-Li bonds, which indicates that electrondensity at the Ni is reserved to form two Li-Ni bonds. In the literature, these descriptions of Ni-olefin complexes usually refer to the dichotomy of Ni(0)-olefin/Ni(II) metallacyclopropane. 2 However, our case represents a twofold down in oxidation state of this dichotomy and hence, a rare and unique form of a Ni(0) metallacyclopropane. S8 4 Stoichiometric Experiments Scheme S4 Reaction A: A Schlenk tube was charged with complex 1 (18.0 mg, 0.029 mmol) via argon trousers and dissolved in precooled THF (1 mL) at 0 °C. The solution was cooled to −78 °C and (E)-(2bromovinyl)benzene (5.4 mg, 3.4 µL, 0.029 mmol, 1 eq.)was added via a Hamilton syringe. After stirring for 30 minutes, hexylMgBr (55 µL, 1.05 M, 0.058 mmol, 2 eq.) was added and the reaction was stirred overnight at −20 °C. The reaction was quenched with water and decane (10 µL, 7.3 mg, 0.051 mmol) was added as an internal standard. GC FID analysis showed 32 % product formation, along with styrene (15%) and substrate homocoupling (22%). Reaction B: A Schlenk tube was charged with complex 1 (22.6 mg, 0.036 mmol) via argon trousers and dissolved in freshly dried (Na/K alloy) and precooled d 8-THF (1 mL) at 0 °C. The solution was cooled to −78 °C and (E)-(2-bromovinyl)benzene (4.1 µL, 6.6 mg, 0.036 mmol, 1 eq.) was added via a Hamilton syringe. The reaction was stirred for 30 minutes, quenched by addition of water and rinsed with EtOAc.

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Palladium-Catalyzed Hydrophenylation of Alkynes with Sodium Tetraphenylborate under Mild Conditions

Abstract: In an aqueous solution of acetic acid, PdCl2(PPh3)2 showed high catalytic activity for the hydrophenylation of both terminal and internal alkynes with sodium tetraphenylborate (NaBPh4) under mild conditions, affording phenyl alkenes in moderate to excellent yields.

Cited by 61 publications

References 30 publications

Rhodium‐ and Palladium‐Catalyzed Hydroarylation of Propargylic Amines with Arylboronic Acids

Rhodium‐ and Palladium‐Catalyzed Hydroarylation of Propargylic Amines with Arylboronic Acids

Efficient Palladium‐Catalyzed Double Arylation of Phosphonoalkynes and Diarylalkynes in Water: Use of a Dinuclear Palladium(I) Catalyst

A Highly Reduced Ni–Li–Olefin Complex for Catalytic Kumada–Corriu Cross-Couplings

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