1.1- Dimethyl-2,2-diphenylethylene

C5D5N above 80 °C, it gains the characteristic color of phosphorus ylide, and signals of phosphorus ylides and cyclosilathianes appear in the H, 13C, and 31P NMR spectra. In the presence of an equivalent amount of benzo-phenone in this solution, 1,1-dimethyl-2,2-diphenylethylene and Ph3PO are formed in 53% yield at 100 °C for 10min. This indicates that the retro-Wittig decomposition of 20a occurs in the solution (Scheme 23, equilibrium a). Probably, phosphorus ylide is also formed in the equilibrium bimolecular reaction between two betaine molecules (Scheme 23 equilibrium b). The ratio of the contributions of these two reactions is strongly determined by the solvent and temperature. 

Metalation of olefins,3 Metalation of 1,1 -dimethyl-2,2-diphenylethylene (1) with n-BuLi-TMEDA complex gives the anion (2) in good yield as shown by the reaction... 

Dimsyl anion 88 is known to add to styrene, and to 1,1-diphenylethylene in the presence of a base, forming 3-arylpropyl methyl sulfoxides121. Treatment of ( )-3,3-dimethyl thiacyclo-oct-4-ene-l-oxide 89 with n-BuLi gave exo-4,4-dimethyl-2-thiacyclo-[3.3.0]octane 2-oxide 90, a bicyclic addition product of the internal double bond. A similar cyclization was observed in the reaction of 91 with n-BuLi122. 

As mentioned earlier, an electrode reaction implies some orientation effect because a substrate molecule must be fairly close to the electrode surface. The following pairs of cis and trans isomers were reported to exhibit identical reduction potentials l,2-dimethyl-l,2-diphenylethylenes (Weinberg and Wienberg 1968) l,2-bis(4-cyanophenyl)-l,2-bis(4-methoxyphenyl) ethylenes (Leigh and Arnold 1981) and l,2-bis(4-acetylphenyl)-l,2-diphenylethylenes (Wolf et al. 1996). 

Particularly, the trans isomer of l,2-dimethyl-l,2-diphenylethylene is coplanar and the cis isomer is noncoplanar. However, both isomers are oriented in an identical manner within the electrode space and electric field (Homer and Roder 1969). The energy needed for such an orientation is not markedly reflected in the value of a potential. For oxidation potentials, there are also data that these potentials are not sensitive to diastereoisomerism (Fukui et al. 2007). 

The bromide-lithium exchange of l,l-dibromo-2,2-diphenylethylene (88) was thoroughly examined by Maercker and coworkers. It could be shown that the number of side-products drastically decreases when LiDBB instead of metallic lithium is used as lithiation agent. The reaction was performed in THF at low temperatures by addition of the solution of the geminal dibrominated aUcene to the solution of LiDBB (Scheme 32). By this method, l,l-dilithio-2,2-diphenylethylene (89) could be obtained in 36% yield together with the 1,4-dilithium compound 48 and monolithiated 47 (51 and 2%, respectively). The yields were determined after trapping the reaction mixture with dimethyl sulphate. 

Diethynylphenol, 3244 2,3-Dimethyl-l,3-butadiene, 2407 6,6-Dimethylfulvene, 2967 1,1-Diphenylethylene, Oxygen, 3642 Formaldehyde oxide polymer, 0419... 

The general characteristics of anionic copolymerization are very similar to those of cationic copolymerization. There is a tendency toward ideal behavior in most anionic copolymerizations. Steric effects give rise to an alternating tendency for certain comonomer pairs. Thus the styrene-p-methylstyrene pair shows ideal behavior with t = 5.3, fy = 0.18, r fy = 0.95, while the styrene-a-methylstyrene pair shows a tendency toward alternation with t — 35, r% = 0.003, i ii 2 — 0.11 [Bhattacharyya et al., 1963 Shima et al., 1962]. The steric effect of the additional substituent in the a-position hinders the addition of a-methylstyrene to a-methylstyrene anion. The tendency toward alternation is essentially complete in the copolymerizations of the sterically hindered monomers 1,1-diphenylethylene and trans-, 2-diphe-nylethylene with 1,3-butadiene, isoprene, and 2,3-dimethyl-l,3-butadiene [Yuki et al., 1964]. 

Dimethyl-1,3-butadiene, 2401 6,6-Dimethylfulvene, 2962 1,1-Diphenylethylene, Oxygen, 3635 Formaldehyde oxide polymer, 0418 f l,5-Hexadien-3-yne, 2284... 

Diphenylethylene glycol dimethyl ether exo, ryn-2,7-Dimethoxy-bicyclo [2.2.1 ] heptane exo- 2-methoxybicyclo [2.2. l] heptane... 

The preparation of other stereospecific hydrogenation catalysts such as ruthenium dichloride((S)-(6,6 -dimethoxybiphenyl-2,2 -diyl)bis[bis(3,5-dimethyl-xylene)((R,R)-2-diphenylethylene-diamine)] is provided (2). Other suitable ligands such as l,2-bis(2,5-dimethylphospholano)benzene are described (3). 

Aminoquinazolinone derivatives were oxidized with the optically active oxidant lead tetra-(S)-2-methylbutanoate in the presence of excess styrene, E)-, 2-diphenylethylene and dimethyl fumarate. The aziridine was obtained with asymmetric induction only from ( )- 1,2-diphenyl-ethylene, but the enantiomeric excess was not reported31. 

The reaction of pentacarbonyldiphenylcarbenetungsten with xs of 2,3-dimethyl-l,3-butadiene at 70°C results in the formation of isoprene and 1,1-diphenylethylene ... 

D. Resolution of the dl-diamine (R,R)-(+)-N,N -Dimethyl-1,2-diphenylethylene-diamine and (S,S)-(-)-N,N -Dimethyt-1,2-diphenylethylenediamine. A 1-L, round-bottomed flask, equipped with a magnetic stirring bar and a water condenser, is charged with pure dl-diamine (12 g, 0.05 mol), natural L-(+)-tartaric acid (7.1 g, 0.05 mol) (Note 14) and absolute ethanol (350 mL). The heterogeneous mixture is brought to reflux and the precipitate dissolves completely (Note 15). After 30 min the solution is allowed to cool to room temperature and stand overnight (17 hr). The precipitate is collected by filtration and washed with ethanol (2 x 50 mL). The salt is added to a mixture of aqueous 35% (w/w) NaOH (30 mL), demineralized water (100 mL) and Et20 (100 mL). The solution is stirred for 30 min, and the phases are separated. The... 

Molecular oxygen can add to the double bonds of olefins such as styrene, 1,1-diphenylethylene, dimethyl- and diethyl-ketene, vinyl acetate, cyclopentadiene and cyclohexadiene with formation of polymeric peroxy compounds. The course of the reaction corresponds to that of a mixed polymerization 1 r>2 3 4b d... 

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