Preparation of polymer-supported phosphine from ferrocene for palladium-catalyzed Suzuki-Miyaura cross-coupling reactions

Polymer-supported phosphine ligand 3b derived from ferrocene was prepared,and applied in palladium-catalyzed Suzuki- Miyaura reactions.A range of aryl bromides can couple with phenylboronic acid to obtain corresponding biaryls in excellent yields. The recycling of the polymer-bound catalyst was tested without adding palladium.     

Isonitriles as efficient ligands in Suzuki-Miyaura reaction

Isonitrile palladium complexes [(RNC)₂PdCl₂] were prepared and tested in Suzuki reaction of 4-chloroanisol. (AdNC)₂PdCl₂ was found the most effective catalyst and was used in phenylation of several chloro and bromoaromatic substrates.     

Suzuki-Miyaura and Hiyama reactions catalyzed by orthopalladated triarylphosphite complexes

Orthometallated, dimeric, and monomeric palladium complexes with triphenylphoshito ligands and square-planar complexes of the type PdCl₂[P(OR)₃]₂ (where R=Ph, m-MeC₆H₄, o-MeC₆H₄, C₆H₃-2,4-^tBu₂) were applied in the Suzuki-Miyaura and the Hiyama reactions leading to the same product, 2-Mebiphenyl. The desired product was obtained in high yield in reactions performed in ethane-1,2-diol with Cs₂CO₃ as a base. The optimized procedure was also applied to the synthesis of other biphenyl derivatives, and in most cases the Suzuki-Miyaura procedure led to higher yields of the product.     

One-pot synthesis of fluorinated terphenyls by site-selective Suzuki-Miyaura reactions of 1,4-dibromo-2-fluorobenzene

The Suzuki-Miyaura reaction of 1,4-dibromo-2-fluorobenzene with two equivalents of arylboronic acids gave fluorinated para-terphenyls. The reaction with 1 equiv of arylboronic acid resulted in site-selective formation of biphenyls. The one-pot reaction of 1,4-dibromo-2-fluorobenzene with two different arylboronic acids afforded fluorinated para-terphenyls containing two different terminal aryl groups.     

Site-selective Suzuki-Miyaura reactions of 2,3,5-tribromo-N-methylpyrrole

The first Suzuki-Miyaura reactions of 2,3,5-tribromo-N-methylpyrrole are reported. These reactions proceed with very good site-selectivity in favour of position 5 which is more reactive than position 2, due to steric reasons. The second attack occurs at position 2 which is more electron deficient than position 3.     

Suzuki-Miyaura reactions of N-protected tribromopyrazoles. Efficient and site-selective synthesis of 3,4,5-triaryl-pyrazoles, 3,5-diaryl-4-bromopyrazoles and 5-aryl-3,4-dibromopyrazoles

Suzuki-Miyaura reactions of N-protected tribromopyrazoles were studied. The reactions proceed with excellent site-selectivity. The first attack occurs at position 5, while the second and third attack occur at positions 3 and 4, respectively. A variety of 3,4,5-triaryl-pyrazoles, 3,5-diaryl-4-bromopyrazoles, and 5-aryl-3,4-dibromopyrazoles were efficiently prepared. The products are not readily available by other methods.     

Pd-EDTA as an efficient catalyst for Suzuki-Miyaura reactions in water

PdCl₂-EDTA complex 1 is an efficient catalyst for the Suzuki-Miyaura reactions of aryl and heteroaryl halides with aryl(heteroaryl)boronic acids in water at 20-100 °C. Aryl iodides and bromides undergo the cross-coupling with turnover numbers (TON) up to 97,000 and turnover frequencies (TOF) up to 582,000 h⁻¹.     

Site-selective Suzuki-Miyaura reactions of the bis(triflate) of 1,3-dihydroxyanthraquinone

Various aryl-substituted anthraquinones were prepared by palladium(0)-catalyzed Suzuki-Miyaura cross-coupling reactions of the bis(triflate) of 1,3-dihydroxyanthraquinone. A very good site-selectivity in favor of position 1 was observed which can be explained by the electronic influence of the neighboring carbonyl group.     

Triphenylphosphine chalcogenides as efficient ligands for room temperature palladium(II)-catalyzed Suzuki-Miyaura reaction

A simple catalytic system based on PdCl₂ and triphenylphosphine chalcogenides (PPh₃X; X = O, S, Se) is found to be highly effective (up to 97% isolated yield) in the room temperature Suzuki-Miyaura reactions. Under the same experimental conditions, triphenylphosphine chalcogenides as ligands show superior activities compared to free triphenylphosphine.     

cis-Fashioned palladium (II) complexes of 2-phenylbenzimidazole ligands: Synthesis, characterization, and catalytic behavior towards Suzuki-Miyaura reaction

Reaction of 2-arylbenzimidazole with PdCl₂(CH₃CN)₂ in CH₂Cl₂ affords benzimidazole palladium (II) complexes in high yields. The structure of complexes C1, C2, and C3 has been confirmed by X-ray structure analysis. The configuration of complexes depends on the substituent on the 2-position of benzimidazole. Phenyl affords the complexes in cis-fashion due to π-π stacking of phenyl and benzimidazole. Tolyl affords the complex in trans-fashion. The catalytic studies show that cis-configured 2-phenylbenzimidazole palladium (II) complexes are highly efficient catalysts in the Suzuki-Miyaura reaction.     

Site-selective Suzuki-Miyaura reactions of the bis(triflate) of 1,3-dihydroxythioxanthone

The palladium(0)-catalyzed Suzuki cross-coupling reaction of the bis(triflate) of 1,3-dihydroxythioxanthone afforded various aryl-substituted thioxanthones. The reactions proceeded with very good site-selectivity in favour of position 3, due to steric reasons.     

Site-selective Suzuki-Miyaura reactions of 2,3-dibromo-1H-inden-1-one

The first transition metal-catalyzed cross-coupling reactions of 2,3-dibromo-1H-inden-1-one are reported. The Suzuki-Miyaura reaction of 2,3-dibromo-1H-inden-1-one with 2 equiv of arylboronic acid gave 2,3-diaryl-1H-inden-1-ones. The reaction with 1 equiv of arylboronic acid gave 2-bromo-3-aryl-1H-inden-1-ones with very good site-selectivity. The one-pot reaction of 2,3-dibromo-1H-inden-1-one with two different arylboronic acids afforded 2,3-diaryl-1H-inden-1-ones containing two different terminal aryl groups.     

Salen and half-salen palladium(II) complexes: synthesis, characteriztion and catalytic activity toward Suzuki-Miyaura reaction

Salen and half-salen palladium(II) complexes (salden)Pd (1, salden=N,N′-bis(3,5-di- tert-butylsalicylidene)-1,2-dimethylethylenediamine), (hsalph)PdCl (2, hsalph=3,5-di-tert- butylsalicylidene-1-iminophenylene-2-amine), and (salph)Pd (4, salph=N,N′-bis(3,5-di-tert- butylsalicylidene)-1,2-phenylenediamine) were prepared and structurally characterized by X-ray crystallography. Complex 2 proved to exhibit high catalytic activity toward Suzuki-Miyaura reaction. Polyaromatic C₃-symmetric derivatives and various fluorinated biphenyl derivatives were readily achieved in good yields using Suzuki-Miyaura reaction catalyzed by complex 2.     

Monomeric triphenylphosphite palladacycles with N-imidazole ligands as catalysts of Suzuki-Miyaura and Sonogashira reactions

Three monomeric triphenylphosphite palladacycles of the formula [PdCl(P-C)(im)], where P-C = P(OC₆H₄)(OC₆H₅)₂, im = 1-methylimidazole, 2, 1,2-dimethylimidazole, 3, and 1-butylimidazole, 4, were obtained in reaction of [PdCl(P-C)]₂, 1, with the respective imidazoles. These complexes exhibited high catalytic activity in the Suzuki-Miyaura reaction in ethane-1,2-diol and in the Sonogashira reaction in ionic liquids, [bmim]BF₄ and [bmim]PF₆. While the application of two imidazoles per palladium caused improvement of the reaction yield, an inhibiting effect was found in both reactions when 1-methylimidazole or 1-butylimidazole was used in 20-fold excess relative to palladium.     

Regioselective Suzuki-Miyaura reactions of the bis(triflate) of 1,2,3,4-tetrahydro-9,10-dihydroxyanthracen-1-one

The palladium(0)-catalyzed Suzuki cross-coupling reaction of the bis(triflate) of 1,2,3,4-tetrahydro-9,10-dihydroxyanthracen-1-one afforded various aryl-substituted 1,2,3,4-tetrahydroanthracen-1-ones. The reactions proceeded with very good site-selectivity in favour of position 10, due to electronic reasons.     

Convenient synthesis of photochromic symmetrical or unsymmetrical bis(heteroaryl)maleimides via the Suzuki-Miyaura cross-coupling reaction

A general method for the synthesis of symmetrical or unsymmetrical bis(heteroaryl)maleimides by a one-pot procedure involving Suzuki-Miyaura cross-coupling sequence was developed on the basis of the reaction of 3,4-diiodo-1-benzyl-1H-pyrrole-2,5-dione with cyclic boronate esters using PdCl₂(dppf) as the catalyst. Photochromic properties of the products were examined.     

One-pot conversion of 1,1-dibromoalkenes into internal alkynes by sequential Suzuki-Miyaura and dehydrobromination reactions

A protocol for the one-pot synthesis of internal alkynes from 1,1-dibromoalkenes is reported. The method is hinged upon the Suzuki-Miyaura cross-coupling of 2-aryl- or 2-heteroaryl-1,1-dibromoalkenes with aryl or heteroaryl boronic acids or borate esters followed by dehydrobromination of the intermediate coupled products. Yields up to 89% were obtained.     

Polymer-supported palladium catalysed Suzuki-Miyaura reactions in batch and a mini-continuous flow reactor system

A polymer-supported palladium(II) salen-type complex exhibited catalytic activity in the cross-coupling reaction of various aryl bromides and heteroaryl bromides with phenylboronic acid in a mini-continuous flow reactor system at elevated temperatures in a phosphine-free system. The reaction was also performed in batch using a number of different solvent systems in order to optimise conditions. The catalytic mini-reactor can be used repeatedly over several cycles in the Suzuki-Miyaura cross-coupling reaction. While the diameter of the flow channel is 3 mm, the macroporous resin supported catalyst is solvent expanded to completely fill the channel. Consequently, the liquid path is through the micro channels of the macroporous resin structure. Intensification of the process over the stirred batch reaction is through increased reagent-catalyst contact and results in a 20-fold increase in the rate of reaction. The residence/space time on the reactor is 10.5 min, compared to 24 h in batch, which means that a diversity of starting materials can be screened over a short period of time. To demonstrate the utility of the system, a diversity of aryl and heteroaryl bromides have been studied.     

PEPPSI-Pd-NHC catalyzed Suzuki-Miyaura cross-coupling reactions in aqueous media

A series of unsymmetrical 1,3-disubstituted benzimidazolium chlorides were synthesized as N-heterocyclic carbene (NHC) precursors. These compounds were used to synthesize of the PEPPSI-type palladium NHC complexes. The structures of all compounds were characterized by ¹H NMR, ¹³C NMR, FT-IR spectroscopy and elemental analyses. The catalytic activity of the PEPPSI-type palladium–NHC complexes has been evaluated with respect to the Suzuki-Miyaura cross-coupling reactions of phenyl boronic acid with various aryl halides in aqueous media.     

A one-pot,two-step synthesis of 3-deazacanthin-4-ones via sequential Pd-catalyzed Suzuki-Miyaura and Cu-catalyzed Buchwald-Hartwig reactions

3-Deazacanthin-4-one and nine analogues, including the 8-aza analogue, were prepared rapidly and in high yields from 8-iodoquinolones and 2-chloro(het)arylboronic acids. The strategy involves construction of the central B ring via concomitant Pd-catalyzed Suzuki-Miyaura CC and Cu-catalyzed Buchwald-Hartwig CN coupling reactions.