Biphenyl 4,4 -dicyano

In a similar approach, Demuth and coworkers used PET and employed 1,4-dicyano-tetramethylbenzene (DCTMB) and l,l -biphenyl (BP) to form radical cations as 5-11 from tetraenes as 5-10. 

Since the publication of CHEC-II(1996), there have been very few examples related to the reactivity of substituents attached to ring carbon atoms. One case involves the reaction of 3-benzylidene-2,3-dihydro-2-methyl-l,2-benzothiazin-4-one 1,1-dioxide 163 with the alkylidenephosphorane derived from salt 164 forming the tricyclic-fused ring compound 165 (Scheme 20) <1996J(P1)2541>. This material 165 was oxidized with 2,3-dichloro-5,6-dicyano-l,4-benzoquinone (DDQ) affording the biphenyl 166. Ring-opened product 167 was produced from 165 upon exposure to />-toluene-sulfonic acid and heat. 

Demuth et al. recently developed an efficient radical cationic cyclization of functionalized polyalkenes using 1,4-dicyano-tetramethylben-zene (DCTMB) as an acceptor and biphenyl (BP) as co-sensitizer [43]. The transformation is in general highly stereo- and chemoselective and the substitution pattern of the polyalkene allows the construction of either five-or six-membered rings (Sch. 21). So far, this methodology has been applied for the synthesis of several natural products such as stypoldione, hydroxyspongianone and abietanes, respectively [43]. 

Photoinduced electron transfer from donors such as prenyl acetate, geranyl acetate, all-/ra/w-famesyl acetate, and all-/ra j-geranylgeranyl acetate to 1,4-dicyano-2,3,5,6-tetramethylbenzene, 1,4-dicyanonaphthalene, and 9,10-dicya-noanthracene in the presence of l,r-biphenyl as co-donor in acetonitrile produces the radical cation of biphenyl and the radical anion of the electron acceptors. Geranyl acetate is observed to photocyclise, and the mechanism of this process which involves reaction of its radical cation with water is discussed. Allyl glycosides (76) can be photodeprotected to give (77) via (78) by irradiating with di-t-butyl peroxide in the presence of bromotrichloro-methane. ... 

The radical anion derived from 2-cyanodiphenyl ether underwent reversible dimerization resulting in a dianion relatively resistant towards further chemical reaction. The products observed after electrolysis were mainly phenol, diphenyl ether and 2, 4-dicyano-3-phenoxy biphenyl. The structure of the isolated biphenyl suggested that the radical anion dimerization had occurred via 2-4 coupling. 

In the case of less soluble biphenyls such as 4,4 -dicyano- or 4,4 -diacetylbi-phenyl, chloroform was used for extraction. The reaction mixture was poured into chloroform (150 ml) and washed with 3% HCl solution followed by water (100 ml). 

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