Terphenyl synthesis

In the event, treatment of 622 (X = Br or Cl, Y = Br or I) with 3 equivalents of an aryl Grignard reagent followed by an electrophilic quench gave m-terphenyls 629 in good yield (60-85%). The reaction is not subject to steric hindrance (for example, Ar = 2,6-dimethylphenyl, mesityl, 1-naphthyl or 2-anisyl). It provides a one-pot route to m-terphenyls substituted at the 2 position (or, looked at another way, 2,6-diaryl benzene derivatives), difficult to obtain in other ways. This m-terphenyl synthesis has been used to create two new classes of cyclophanes (cupped- and cappedophanes) . ... 

A convenient one pot route to various biphenyls [12], p-terphenyls [13] as well as m-terphenyls [6], starting from suitably substituted polyhalobenzenes, was developed in our laboratories in the mid 1980s. The protocol involves a tandem aryne generation - nucleophilic capture sequence and is described in detail here only in conjunction with the synthesis of m-terphenyls. 2,6-Dichloroiodoben-zene 14 is frequently employed as the polyhalobenzene required for the m-terphenyl synthesis. It is readily prepared from commercially available... 

The penultimate product of our m-terphenyl synthesis 19, (Scheme 1), through reaction with electrophiles, allows for the direct introduction of a variety of functional groups at the internal position of the central m-terphenyl ring [6]. Halogens (Br or I) could be introduced by appropriate quench of the reaction prior to work-up. Even though the bromo derivatives 23, 32 and the iodo derivatives 24, 28, and 33 (Scheme 2) were obtained in yields ranging from... 

An elegant synthesis method which is specific to sulfone polymers containing phenyl—phenyl linkages (such as PPSF) is the nickel-catalysed coupling of aryl dihahdes. The scheme for this synthesis involves a two-step process. First, an aromatic dihaUde intermediate is formed which carries the backbone features of the desired polymer. This aromatic dihahde intermediate is then self-coupled in the presence of sero-valent nickel, triphenylphosphine, and excess sine to form the biphenyl- or terphenyl-containing polymer. AppHcation of this two-step scheme to PPSF can be depicted as follows ... 

This metathetical route was recently extended to the synthesis of amidinato complexes of Al, Ga, and In containing very bulky amidinate ligands with 2,6-Pr CgHs, adamantyl, m-terphenyl or 9-tiiptycenyl substituents at the central carbon atom. ... 

Hexa(oligophenyl)benzenes (e. g. 31 or 33) present one possible approach to the realization of this aim. Two efficient synthetic routes have been elaborated for the preparation of hexa(terphenyl)- and hexa(quaterphenyl)benzene. The first, involving palladium-catalyzed trimerization of diarylacetylenes [54] as the key step, was demonstrated by the synthesis of a hexakis-alkylated hexa(terphenyl)benzene derivative 31 from the corresponding bis(terphenyl) acetylene (32). The peripheral tert-alkyl substituents serve to solubilize the molecule. 

Nickel catalysis has been used in a sequential synthesis of terphenyls, starting with 2-, 3-, or 4-bromophenyl neopentanesulfonates. Conventional Pd-catalyzed Suzuki conditions were used for the first step involving coupling of the bromide and then nickel catalysis was utilized for coupling the sulfonate. 

General procedure for the reaction of an o-substituted aryl iodide with an arylboronic acid. Synthesis of terphenyl derivatives. 

This convenient process has been applied to the synthesis of an interesting heterocyclic analogue of j -terphenyl that incorporates three different first-row,... 

Scheme 13 Attempted synthesis of phosphaquinoid compounds carrying m-terphenyl ligand [13]...

For synthesis on a larger scale, it has been found that the workup described by Hart et al is impractical, and an alternative has been published.27 This differs in that aryl halide by-products are removed by distillation under reduced pressure. The residue is then refluxed in EtOH, and filtration effects the recovery of crude halogenated terphenyl product. Sublimation under reduced pressure affords the pure product in up to 75% yield. 

Kimura et al. also presented the synthesis and characterization of a second-generation ruthenium(II) bis(terphenyl)polyphenylene dendrimer 52, an attractive molecule with regard to its electrochemical and photochemical pro-... 

Similar routes have been used for the synthesis of other polynitrophenylenes. 1,3,5-Tris(2,4,6-trinitrophenyl)-2,4,6-trinitrobenzene (160) is synthesized from the reaction of 1,3,5-trichloro-2,4,6-trinitrobenzene with three equivalents of picryl chloride in the presence of activated copper powder in refluxing mesitylene. " 2,2",4,4, 4",6,6, 6"-Octanitro-m-terphenyl (161) has been synthesized from picryl chloride and l,3-dichloro-4,6-dinitrobenzene. ... 

Power and co-workers reported the synthesis and characterization of a new type of sterically crowded diarylstannylene (172), that bears two bulky m-terphenyl type ligands (2,6-Mes2C6H3) and exists as a monomer even in the solid state (Scheme 14.75). 

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