1,3,5,7-Octatetraene, 1,8-diphenyl

The overall transformation is the conversion of the carbon-sulfur bonds bond to a carbon-carbon double bond. The original procedure involved halogenation of a sulfide, followed by oxidation to the sulfone. Recently, the preferred method has reversed the order of the steps. After the oxidation, which is normally done with a peroxy acid, halogenation is done under basic conditions by use CBr2F2 or related polyhalomethanes for the halogen transfer step.92 This method was used, for example, to synthesize 1,8-diphenyl-1,3,5,7-octatetraene. 

Electro-optical modulators are other examples whose efficiency is enhanced in the presence of ion radicals. These devices are based on sandwich-type electrode structures containing organic layers as the electron-hole-injecting layers at the interface between the electrode and the emitter layer. The presence of ion radicals lowers the barrier heights for the electron or hole injection. Anion radicals (e.g., anion radicals from 4,7-diphenyl-l,10-phenanthroline—Kido Matsumoto 1998 from tetra-arylethynyl-cyclo-octatetraenes— Lu and co-workers 2000) or cation radicals (e.g., cation radicals from a-sexithienyl—Ku-rataetal. 1998 1,1 -diphenyl-2-[phenyl-4-Ar,ALdi(4 -methylphenyl] ethylene—Umedaand co-workers 1990, 2000), all of them used as electron or hole carriers. 

Dienylation of alkynes proceeds in the presence of Co catalysts, and the conjugated diene system is retained in the adducts. The conjugated trienes 120 and 121 are obtained from 2-butyne (119) and butadiene [44]. The dienylation occurs to give the conjugated l,8-diphenyl-l,3,5,7-octatetraene (122) by attack of two phenylacetylene molecules to both side of butadiene [42a]. 

Three unique di-diene have been utilized by Meek (9, 10) in the preparation of Diels-Alder copolymers. Reaction of 1,8-diphenyl-octatetraene with ftts-maleimides in refluxing chloroform for several days affords high yields of polymers with softening temperatures well over 300°, but low intrinsic viscosities. The copolymerization of 1,5-di(9-anthryl)-l,4-pentadiene-3-one and anthralazine with fo s-maleimides employs the diene nature of anthracene to obtain polymers with... 

Fig. 22.5. Freezing point curves for naphthalene + 1.8. diphenyl-octatetraene. ...

Under the usual conditions of the Perkin reaction, cinnamaldehyde gives an excellent yield of 5-phenyl-2,4-pentadienoic acid 890 but decarboxylation occurs when it is heated with phenylacetic acid and acetic anhydride in the presence of lead(n) oxide, 1,4-diphenyl-1,3-butadiene being formed in 30% yield,891 and under these conditions two equivalents of cinnamaldehyde and one of succinic acid give l,8-diphenyl-l,3,5,7-octatetraene.892... 

Irradiation of solutions of cycloheptatrieneiron tricarbonyl at low temperatures followed by addition of diphenylacetylene produces the [2 + 6] adduct, 7,8-diphenyl-bicyclo[4,2,l]octa-2,4,7-triene similar results were obtained with cyclo-octatetraene-iron tricarbonyl and related compounds. The mechanism suggested involved photo-induced replacement of one of the olefin bonds or carbon monoxide ligands in the complexes by a solvent molecule, thermal replacement of the solvent by the acetylene, and an intramolecular cycloaddition. ... 

Syntheses have been reported of barrelene (505) and of Nenitzescu s hydrocarbon (503) on a reasonable scale and without some of the difficulties that attend the previously published routes." " The preparation of (503) is of central importance, it being obtained by the oxidative bisdecarboxylation of the cyclo-octatetraene-maleic anhydride Diels-Alder adduct (502) with dicarbonylbis(triphenylphosphine)-nickel in diglyme at reflux. Cycloaddition of (503) to 2,5-dimethyI-3,5-diphenyl-cyclopentadienone in hot benzene afforded (504) and its endo-isomer. Photolysis of (504) yielded (505) in 24% yield from cyclo-octatetraene. The thermally labile benzene-maleic anhydride [4 + 2] cycloadduct (506) was obtained in similar fashion from (502). A review of the mechanisms of pyrolysis of (503) and a number of isomers and benzo-fused (CH) derivatives (collectively termed Nenitzescu s hydrocarbons) has appeared." ... 

The preparation of copper(i) trifluoroacetate and the formation of some phosphine and olefin complexes from it are described. Triphenylphosphine forms mono-, bis-, and tris-phosphine complexes, but evidence for co-ordination of four phosphine groups could be obtained only with bis(diphenyl-phosphino)ethane. The tris(triphenylphosphine)copper(i) trifluoroacetate is also formed by reduction of copper(ii) trifluoroacetate with triphenylphosphine in alcoholic solution. Cyclo-octa-1,5-diene forms 1 1 and 1 2 complexes with copper(i) trifluoroacetate, and cyclo-octatetraene forms a 1 2 complex for which the structure (155) is suggested. ... 

Cyclo-octatetraene monoepoxide reacts with 3,6-diphenyl-sym-tetrazine to give the ring-expanded (214) which is oxidized by o-chloranil to give 1,4-diphenyloxonino [4,5-c/]pyridazine. The nature of the products obtained from cyclo-octatetraene... 

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