Bis aromatic

The phenomenon of restricted rotation in the biphenyl series had been amply demonstrated by numerous workers (1), (2), 50), 51). There remained to be explored, however, a variety of mixed bi-aromatics in which one component of the bi-aromatic was a heterocyclic ring. This void was due undoubtedly to the difficulties of synthesis which seriously impeded the rapid development of the study of these types. 

Studies on the Chemistry of Heterocyclics. XVIII. Mixed Bi-Aromatics. 

Coupling of an aryl triflate with an arylstannane is a good mediod for the preparation of biaryls and other bis-aromatic species of all types. Coupling of vinyl groups takes place with retention of stereochemistry. Furdiermore transfer of die allyl group occurs smoothly. 

Bloor, D., Ando, D. J., Fisher, D. A., Hubble, C. L. Solid state reactivity of some bis (aromatic sulphonate) diacetylenes. In Molecular metals. Hatfield, W. E. (ed.). New York Plenum Press 1979, pp. 249 253... 

Quandt G, Hofiter G, Wanner KT (2013) Synthesis and evaluation of N-substituted nipecotic acid derivatives with an unsymmet-rical bis-aromatic residue attached to a vinyl ether spacer as potential GABA uptake inhibitors. Bioorg Med Chem 21 3363-3378... 

Lockhart and Thompson (1977) prepared a dibenzodiaza-crown by treating triglycolyl dichloride n = 2) with a bis(aromatic amine) followed by reduction (method V-12). This method, using the Stetter bis-amide synthesis for ring closure, has been used by others for the preparation of dibenzodiaza-crowns... 

Polyimides are most conveniently prepared by condensation of a bis-aromatic anhydride with a 6w-aromatic amine (Figure 6.13). The first step yields a polyamic acid which can be conveniently dehydrated and cyclised to a polyimide by treatment with acetic anhydride and pyridine under rather mild conditions. This can now be achieved in an organic suspension to yield spherical particulate polyimides [67]. In a typical procedure a polyamic acid precursor is formed in solution in dimethylacetamide (DMAc 10 wt%) by reaction of pyromellitic dianhydride with /7-phenyle-nediamine at room temperature for 2 h. This pre-polymer solution is then suspended in paraffin oil containing a dissolved polymer chosen to function as a steric stabiliser for the DMAc solution. A copolymer of maleic anhydride and octadec-l-ene is very effective. The suspended droplets are kept dispersed by overhead stirring while acetic anhydride and pyridine are added dropwise to induce imidisation, typically reaction proceeds for... 

Xue et al. s studies on the gold(I)-catalyzed spirocyclization of bis(aromatic) alkynes 223 [111] found that addition of AgOTf was required to suppress formation of the tmdesired benzofuran side product 225 (Scheme 52). In the absence of the silver(I) salt, benzofuran 225 only was obtained in excellent yield (95 %). Electron-donating groups at R afforded the spiroacetal 224 in good yield (62-68 %), while electron-withdrawing groups at either R or R resulted in lower yields of the spiroacetal. In one case (R = H, R = OMe), benzofuran 225 was obtained in comparable yield to the spiroacetal product (42 % and 45 %, respectively). 

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