Biaryl compounds

Another area of interest to the industrial sector is the development of a more efficient synthesis of biaryl compounds. This has been accompHshed using a Ni(II)-cataly2ed Grignard coupling reaction with an aryl haUde (86—89). 

Arenediazonium species 1 can be reacted with another aromatic substrate 2, by the Gomberg-Bachmann procedure, to yield biaryl compounds 3. The intramolecular variant is called the Pschorr reaction ... 

In the presence of a precious metal catalyst, aryl halides can undergo dehalo-dimerization to give biaryl products, with varying degrees of selectivity. The major byproduct of this reaction is usually the dehalogenated aryl compound. This type of chemistry is currently one of the very few viable means for the large scale preparation of biaryl compounds. 

The homocoupling of aryl halide to diaryl compounds, known as Ull-mann coupling, is a synthetically useful reaction and has wide applications in material research. Such couplings have been studied in aqueous conditions. In 1970, arylsulfinic acids were coupled with Pd(II) in aqueous solvents to biaryls (Eq. 6.25).53 However, the reaction required the use of a stoichiometric amount of palladium. In the presence of hydrogen gas, aryl halides homocoupled to give biaryl compounds in moderate yields (30-50%) in an aqueous/organic microemulsion (Eq. 6.26).54... 

Combs and coworkers have presented a study on the solid-phase synthesis of oxa-zolidinone antimicrobials by microwave-mediated Suzuki coupling [38], A valuable oxazolidinone scaffold was coupled to Bal resin (PS-PEG resin with a 4-formyl-3,5-dimethoxyphenoxy linker) to afford the corresponding resin-bound secondary amine (Scheme 7.18). After subsequent acylation, the resulting intermediate was transformed to the corresponding biaryl compound by microwave-assisted Suzuki coupling. Cleavage with trifluoroacetic acid/dichloromethane yielded the desired target structures. 

Pershichini 2003 Kotha et al. 2002), which is by far the most versatile synthetic method available for the generation of unsymmetrical biaryl compounds and so was an obvious target for the development of flow... 

Following their studies on the trapping of intermediates in the [5 + 2]-cycloaddition with CO, which led to the [5 + 2 + l]-process, the Wender group found that when related reactions were conducted with aryl alkynes under an atmosphere of CO, a novel four-component [5 + 2 + 1 + l]-product was observed.172 A VCP, an alkyne, and 2 equiv. of CO react to give the biaryl compounds shown (Scheme 78) via the formation of a nine-membered ring intermediate. 

Preparation of the chiral biphenyls and binaphthyls with high enantiose-lectivity can be achieved via substitution of an aromatic methoxyl group with an aryl Grignard reagent using oxazoline as the chiral auxiliary.38 Schemes 8-10 and 8 11 outline the asymmetric synthesis of such chiral biaryl compounds. 

The bromo-aryl groups are first linked by (5,5 )-stilbene diol to form the dibromide 33. Compound 33 is then dilithiated with t-BuLi at —78°C, followed by addition of CuCN. Intermediate 34 is presumably formed during the reaction. Reductive elimination promoted by molecular oxygen provides compound 35 at 77% yield with 93 7 diasteroselectivity. The final biaryl compound ellagi-... 

The biaryl compound (50) forms a complex with diethylaluminium chloride to provide a catalyst able to promote enantioselective reaction between cyclo-pentadiene and methacrolein or acrylates (Scheme 45). The addition of A -tert butyl 2,2-dimethylmalonate to the reaction mixture was found to enhance the enantiomeric excess of the product11311. 

Perylene (199) and its derivative (TBP, 200) have been widely used as blue dopant materials owing to their excellent color purity and stability. Efficient blue emitters with excellent CIE coordinates are found in biaryl compound 2,2 -bistriphenylenyl (BTP, 201) as shown in Scheme 3.62 [145]. A device of structure ITO/TPD/BTP/TPBI/Mg Ag emits bright blue emission with CIE (0.14, 0.11). A maximum brightness of 21,200 cd/m2 at 13.5 V with a maximum EQE of 4.2% (4.0 cd/A) and a power efficiency of 2.5 lm/W have been achieved. 

Solid-phase Suzuki reaction was first used in the preparation of biaryls [248]. One recent example is given by Baudoin et al. for the synthesis of biologically active biaryl compounds (Scheme 3.13) [249]. 

Electroreduction of the cobalt(II) salt in a mixture of either dimethylform-amide-pyridine or acetonitrile-pyridine as solvent, often in the presence of bipyridine, produces a catalytically active cobalt(I) complex which is believed to be cobalt(I) bromide with attached bipyridine ligands (or pyridine moieties in the absence of bipyridine). As quickly as it is electrogenerated, the active catalyst reduces an aryl halide, after which the resulting aryl radical can undergo coupling with an acrylate ester [141], a different aryl halide (to form a biaryl compound) [142], an activated olefin [143], an allylic carbonate [144], an allylic acetate [144, 145], or a... 

It is especially noteworthy that this reaction sequence to ( + )-ancistrocladisine (8) offers the unique possibility of synthesizing a natural biaryl compound with two identical ortho-substituents, e.g, methoxy groups, next to the biaryl linkage (see also the nonstereoselective synthesis of ancistrocladisine as a mixture of all four possible stereoisomers13). 

Substituted dibenzothiophenes 156 react with Grignard reagents to give products of the thiophene ring cleavage. With a chiral Ni catalyst, axially chiral biaryl compounds 157 can be obtained in high enantioselectivities (equation 93) . ... 

The ferrocenylphosphine-nickel catalysts are also applied to asymmetric synthesis of axially chiral biaryl compounds through the cross-coupling reaction. Although initial attempts to this... 

The Suzuki coupling reaction is a powerful tool for carbon-carbon bond formation in combinatorial library production.23 Many different reaction conditions and catalyst systems have been reported for the cross-coupling of aryl triflates and aromatic halides with boronic acids in solution. After some experimentation, we found that the Suzuki cleavage of the resin-bound perfluoroalkylsulfonates proceeded smoothly by using [l,l -bis (diphenylphosphino)ferrocene]dichloropalladium(II), triethylamine, and boronic acids in dimethylformamide at 80° within 8 h afforded the desired biaryl compounds in good yields.24 The desired products are easily isolated by a simple two-phase extraction process and purified by preparative TLC to give the biaryl compounds in high purity, as determined by HPLC, GC-MS, and LC-MS analysis. 

Chiralcel CTA Cellulose triacetate, microcrystalline Amides, biaryl compounds ... 

Tri- and tetrazole aromatase inhibitors Mandelic amide Biaryl compounds Biaryl compounds Polycyclic aromatics Sulfur compounds Phosphorus compounds Nitrogen and cyano compounds... 

Ungeremine. The anti-tumour betaine alkaloid ungeremine (182) [50] was synthesised by Snieckus et al. [51] (Scheme 27) utilising their useful modification of the cross-coupling methodology of Suzuki for biaryl compounds. 

Biaryl bisphosphines, atropisomeric, in hydrogenation, 10, 2 Biaryl-bridged bis(iminooxazolidine) complexes, with Zr(IV) and Hf(IV), 4, 811-812 Biaryl compounds, directed synthesis, 10, 145 Bicyclic arenes, in hexaruthenium carbido clusters,... 

A variation in the procedure for certain amines is to add the diazonium salt to sodium hydroxide in an amount sufficient to form the sodium diazotate. The biaryl compound is formed when the aqueous solution of the diazotate is stirred with an aromatic liquid.4... 

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