Biphenyl, amine-substituted

The radical-generating step is a special case of the decomposition of an azo compound. An important use for this reaction is in the synthesis of biphenyls, by reactions in which a second aromatic molecule is attacked by the aryl radical. Under these conditions, hydrogen abstraction from the intermediate arylcyclohexadienyl radical becomes part of the chain mechanism, with the aryl diazonium ion oxidizing the radical intermediate to give the biphenyl. Aryl diazonium ions generated in the usual way by diazotization of aryl amines can also serve as sources of aryl radicals. Substituted biphenyls can be synthesized by base-catalyzed decomposition of the diazonium salt, usually in the presence of an excess of the aromatic substrate. 

Figure 43 Postsynthetic modification. Thermolysis of Z114O (substituted biphenyl-4,4 -dicarboxylate)3- 5H2O in dimethylfor-mamide results in the deprotection of the t-butylcarbamate group, via the evolution of CO2 and isobutylene, to yield the amine.

As was seen, coordinating amines can be built into the monomer structure to enhance the stability of the ester linkage by generating tetra-coordina te boron. Polymers based on this design have been created using amino-substituted biphenyl-4,4 -diboronic acid interacting with saccharides (Fig. 29). The biphenyl moiety was incorporated to provide a spectroscopic handle to probe... 

IV-substituted and B-substituted borazines are readily prepared by suitable choice of amine and borane starting materials or by subsequent reaction of other borazines with Grignard reagents, etc. Thermolysis of monocyclic borazines leads to polymeric materials and to polyborazine analogues of naphthalene, biphenyl, etc. ... 

Bromomethyl)biphenyl-2-carbaldehyde (45) undergoes ring closure with arylamines to give 6-substituted 5//-dibenz[c.t,]azepinium bromides 46 via initial nucleophilic attack by the amine at the aldehyde function.92... 

In view of this background, we developed a new chiral auxiliary to allow for the first time the efficient asymmetric a-alkylation of sulfonamides [90]. After testing some amine auxiliaries mainly based on proline, which did not show high diastereoselectivities, we synthesized the 4-biphenyl-substituted 2,2-dimethyl-l,3-dioxan-5-amine 108 as a new auxiliary. The racemate obtained according to Erlenmeyer s phenylserine synthesis was resolved with tartaric acid to give both enantiomers. 

The heterocyclic hemi-aminal 44 was formed as a model for the synthesis of the marine alkaloids zoanthamine and zoanthenol and is derived from the cyclic imine formed by the reduction of an appropriated substituted azide <07H(72)213>. A pyrrolidine-fused azepine has been isolated from the venom of the ant Myrmicaria melanogaster and assigned as 45 based upon GC and FT-IR comparison with synthetic material <07JNP160>. The axially chiral doubly bridged biphenyl azepine 46 has been synthesised and used with oxone as an epoxidation catalyst in a biphasic system <070BC501>. 

The 50% phenyl-substituted silicone and 30% biphenyl-substituted silicone stationary phases are moderately polar and contain polarizable aromatic rings that exhibit induced dipoles in the presence of dipolar solutes such as alcohols, phenols, amines, nitriles, ketones, and so forth. They give selectivity with-... 

Substitution of the chlorine atoms in POCI3 by biphenyl-2-ol and o-cyclo-hexylphenol and in chloromethylphosphonic dichloride, CICH2POCI2, by primary aliphatic amines has been investigated. Methylphosphonic dichloride can now be obtained in good yield by a one-step process, i.e. slow addition of MeP(0)(0Me)2 to an excess of refluxing thionyl chloride, and, while the technique can be extended to the ethyl derivative, pure BuP(0)Cl2 could not be prepared. 

The partial rate factors and the isomer distribution in the amination by di-methylamino radical cation of toluene, isopropylbenzene, -butylbenzene, biphenyl and naphtalene are reported in Table 7. These partial rate factors are far the highest ever observed in homolytic substitutions so that the general character of the homolytic amination allows a more relevant analogy to be drawn with the electrophilic substitutions than with the homol5rtic arylation, the only homol5rtic substitution for which numerous and accurate quantitative data exist in homo-cyclic aromatic series. 

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