1,1-Diaryl derivatives

The 3,3 -isomer (54) has been prepared by two routes (71JOC1563) (Scheme 21) cyclization of bibenzyl-2,2 -bisdiazoacetate and dehydrogenation of an octahydro derivative made, in two steps, from cyclohexanone. A 1,1 -diaryl derivative of 54 had previously been prepared, with formation of one indazole ring, by oxidation of a benzoylarylhydrazone with lead tetraacetate and treatment with a Lewis acid [66JCS(C)1527j. Lead tetraacetate oxidation of 54 leads to A- - -bi-3H-indazole (71JOC1563). 

Diaryl derivs. s. 5, 548 from aldehydocarboxylic acids, also lactones, s. M. Semonsky et al.. Coll. 40, 2869 (1975)... 

Thioglycolic acid sulfuric acid 1,1-Diaryl derivatives from ketones s. 19, 837... 

No systematic study of the mass spectra of pyridopyrazines has been noted, but those of 2,3-dialkyl and 2,3-diaryl derivatives have been recorded 750MS97), and mass spectrometry has been used in the elucidation of problems in the reactions of pyrido[2,3-f ]pyrazines with amide ion (including use of and derivatives) (79JHC305), and of pyrido[2,3-f ]pyrazinium salts with indoles (78ZOR431). The mass spectra of some 1-deazaflavins have been recorded (74JCS(P1)1965). 

Furan undergoes phenylation rather than diazo coupling on reaction with ben-zenediazonium salts, and thiophene similarly yields 2- or 2,5-diaryl derivatives rather than coupled products. However, 2,5-dimethylfuran and 2-/-butylfuran give coupled products with 2,4-dinitrobenzenediazonium ion (Scheme 26). 

Diaryl derivatives of the 1,3-oxathiolylium system (29) are prepared by acid-catalyzed cyclization of the /3-keto thioesters (28) which are readily prepared from thioacid salts (27)... 

The reaction has been extended to indazole (67BSF2619) from which both isomers have been obtained, and to pyrazolones (68BSF5019). In the latter system N-, O- and C-aryl and even diaryl derivatives have been isolated from the reaction with l-fluoro-2,4-dinitrobenzene. 

Sulfones are thermally very stable compounds, diaryl derivatives being more stable than alkyl aryl sulfones which, in turn, are more stable than dialkyl sulfones allyl and benzyl substituents facilitate the homolysis by lowering the C—S bond dissociation energy17. Arylazo aryl sulfones, on heating in neutral or weakly basic media at 100°C, yield an aryl and arenesulfonyl radical pair via a reversible one-bond fission followed by dediazoni-ation of the aryldiazenyl radical (see Scheme 2 below)20. However, photolysis provides a relatively easy method for generating sulfonyl radicals from compounds containing the S02 moiety. 

Font M et al. (2006) Structural characteristics of novel symmetrical diaryl derivatives with nitrogenated functions. Requirements for cytotoxic activity. Bioorg Med Chem 14(6) 1942-1948... 

Several other oxazolidinones have been developed for use as chiral auxiliaries. The 4-isopropyl-5,5-dimethyl derivative gives excellent enantioselectivity.91 5,5-Diaryl derivatives are also quite promising.92... 

More recently, the El and electrospray ionization (ESI) mass spectra of 2,5-diaryl- and 2-arylamino-5-aryl-l,3,4-oxadiazoles, as well as their complexes with copper cations, were studied. Under ESI conditions, loss of NH3 and HNCO, from complexes of 2,5-diphenyl-l,3,4-oxadiazole, 2,5-bis(2-pyridyl)-l,3,4-oxadiazole, or 2,5-bis(4-pyridyl)-1,3,4-oxadiazole with copper cation, was observed <2004JMP272>. An unusual elimination of isocyanic acid was found in fragmentation of some protonated 2,5-diaryl derivatives <2002RCM390>. 

Trifluoroborane-etherate was used in this reaction. The same route seems to be quite convenient for the preparation of many other (diphenylmethylene-amino)boranes including dihaloborane derivatives. Similarly, B-monohalo derive atives such as [(C6Hs)2ON—B(C6H5)C1] and B-diaryl derivatives were synthesized by the cited method 47)... 

Historically, the polysilanes are old materials and the first diaryl derivatives were probably prepared in 1924 by Kipping (12). The simplest dialkyl representative poly(dimethylsilane) (PDMS) was described in 1949 (12). These materials were,... 

Sulphoxides and sulphoximines are reduced to thioethers by similar reaction sequences [3, 4], In most cases, the yields of the thioethers are higher (>70%) from the diaryl compounds, than from dialkyl or aryl alkyl derivatives but, when the reductions are conducted in an excess of chloroform, the yields of the thioethers are diminished [3], This observation suggests that the thioethers are reacting with dichlorocarbene and that the dialkyl and aryl alkyl compounds are more susceptible than the diaryl derivatives (Table 11.20). 

The valence tautomerism 251 257 has been proposed to account for the formation of iV-methylthiobenzamide by irradiation (2537 A) in methyl cyanide solution. The valence tautomer 257, R = Me, = Ph, has been detected spectroscopically (p , 2060 cm —N=C=S) either during photolysis at 25° or by heating at 160°. Photochemical oxidative cyclization of 4,5-diaryl derivatives (251, R = R = Ar) analogous to the formation of phenanthrene from stilbene has been reported. Thus, irradiation of the 4,5-diphenyl derivative 251, R = R = Ph, yields the tetracyclic meso-ionic compound (258). ... 

However, when it comes to the more important 2,2-diaryl derivatives (1.25), the routes illustrated in Figure 1.7 are not very useful. For these derivatives the almost universally adopted synthetic method involves the reaction of a l,l-diarylprop-2-yn-l-ol (1.24) with a substituted phenol or naphthol in the presence of an acid catalyst. The acid catalyst can be alumina, an acidic clay or Nafion for heterogeneous reactions, or trifluoroacetic acid, p-toluenesulfonic acid and dodecylbenzenesulfonic acid for reactions carried out in solution. The alkynols are prepared by reaction of a benzophenone (1.22) with a Na or Li derivative of an alkynide, such as the trimethylsilyl acetylide (1.23), (Figure 1.8). ... 

Dithiins are prepared by vapor phase dealkoxylation of 2,5-dialkoxy-l,4-dithianes (from HSCH2CH(OEt)2 + H+) over alumina at 260-265°C (306 — 307). 2,5-Diaryl derivatives can be prepared from Bunte salts (308 Scheme 46) with acid via the intermediate diol (309). 

The reaction of p-iodo- or p-bromo-anisole or of 1-iodonaphthalene with the anion formed from the a,(3-unsaturated nitrile (36) gives 60-70% combined yields of the isomeric nitriles (37) and (38) together with small amounts of the diarylated derivatives (39).135... 

Cathodic reduction potentials of disilenes were determined by cyclic voltammetry56. As shown in Table 18, tetraaryldisilenes are reduced at less negative potentials than dialkyl-diaryl derivatives. This is in sharp contrast to the fact that anodic oxidation potentials are similar for both types of these disilanes (see Table 13). 

Krause, M., Rouleau, A., Stark, H., Garbarg, M. Schwartz, J.-C and Schunack, W. 1996. Structure-activity relationships of novel azomethine prodrugs of the histamine H3-receptor agonist (R)a-methylhistamine from alkylaril to substituted diaryl derivatives. Pharmazie 51, 720-726. 

Configuration of A. /V-disubstituted amidines is thus regularly E, reversed rather than in amidines with a free NH2 group which are Z95. Derivatives with only one substituent at the amino group are in the middle and their conformation may be sensitive to small steric effects. In 24 a tautomeric equilibrium would be degenerate, hence the problem is simplified. In the case of IV,-diaryl derivatives, three forms are possible (24a-c) the fourth would be very improbable for steric reasons. From dipole moments an equilibrium... 

In the cases of PDN6S and PDN6G (Table II), the polymer backbones are known to be predominantly trans planar below their respective transition temperatures (13.16). Similarly, the diaryl derivative poly(bis-p-butylphenylsilane)... 

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