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.     

Site-selective Suzuki cross-coupling reactions of 2,3-dibromobenzofuran

The Suzuki-Miyaura reaction of 2,3-dibromobenzofuran with two equivalents of boronic acids gave 2,3-diarylbenzofurans. The reaction with one equivalent of arylboronic acids resulted in site-selective formation of 2-aryl-3-bromobenzofurans. 2,3-Diarylbenzofurans containing two different aryl groups were prepared from 2,3-dibromobenzofuran in a one-pot protocol by sequential addition of two different boronic acids.     

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 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.     

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.     

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.     

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.     

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.     

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.     

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.     

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.     

C-H activations on a 1H-1,4-benzodiazepin-2(3H)-one template

Air stable benzodiazepine containing palladacycles were synthesized by a C-H activation reaction and studied by mass spectrometry and X-ray crystallography. Catalytic C-H functionalizations of 1-methyl-5-phenyl-1H-1,4-benzodiazepin-2(3H)-one with diphenyliodonium hexafluorophosphate led to a mixture, which included the starting material and the expected product 1-methyl-5-(2′-biphenyl)-1H-1,4-benzodiazepin-2(3H)-one.     

Synthesis of 1-arylidene-2,3-dihydro-1H-inden-2-ols through a tandem carbopalladation/Suzuki-Miyaura sequence

A regio- and stereoselective synthesis of arylidene indenols has been developed. The key step involves a palladium-catalyzed tandem carbocyclization/Suzuki-Miyaura sequence.     

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.     

Synthesis of stereodefined 1-aryl(heteroaryl) substituted 1,2-bis(2-bromopyridin-3-yl)ethenes by selective tandem Suzuki-Miyaura cross-coupling reactions

A protocol for the synthesis of stereodefined 1-aryl(heteroaryl) substituted 1,2-bis(2-bromopyridin-3-yl)ethenes by tandem Suzuki-Miyaura cross-coupling reactions and an example of convention into 5-phenyl-1,10-phenanthroline are described.     

Palladium-catalyzed Suzuki-Miyaura couplings of potassium aryl trifluoroborates with 4-tosyloxycoumarins or 4-tosyloxyquinolin-2(1H)-one

Pd(PPh₃)₄ catalyzed Suzuki-Miyaura cross-coupling reactions of 4-tosyloxycoumarins or 4-tosyloxyquinolin-2(1H)-one with various potassium aryl trifluoroborates afforded the corresponding 4-substituted coumarins or 4-substituted quinolin-2(1H)-ones in good to excellent yield.     

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.     

One-step synthesis of reusable, polymer-supported tri-alkyl phosphine ligands. Application in Suzuki-Miyaura and alkoxycarbonylation reactions

A simple, efficient one-step route to polystyrene-supported trialkylphosphine ligands is reported. These polymer-supported alkyl phosphine ligands proved to be highly active for Suzuki-Miyaura reactions and in alkoxycarbonylation reactions. The palladium loaded polymer-supported catalysts can be recycled several times with only minimal loss of catalyst activity.     

An improved protocol for ligandless Suzuki-Miyaura coupling in water

Using a reverse order of addition of reagents, PdCl₂ and Pd(OAc)₂ are efficient catalysts for the Suzuki-Miyaura reactions in water. The ligandless and mild conditions, the high stability of the catalytic system, short reaction time and good to excellent yields are important features of this protocol.     

Divergent synthesis of arylated pyridin-2(1H)-one derivatives via metal-catalysed cross-coupling processes

1,5-Di(hetero)arylated-pyridin-2(1H)-one derivatives have been readily obtained in good yields starting from 2-fluoro-5-pyridylboronic acid. The sequence comprises three steps: (i) palladium-catalysed Suzuki-Miyaura reaction; (ii) base-catalysed hydrolysis; (iii) copper-catalysed C-N coupling. X-ray crystal structures are reported for selected pyridin-2(1H)-one derivatives. These compounds are of interest as new scaffolds for drug discovery.