1.5- dimethyl-2,4-diaryl

Cychc carbonates are prepared in satisfactory quaUty for anionic polymerization by catalyzed transesterification of neopentyl glycol with diaryl carbonates, followed by tempering and depolymerization. Neopentyl carbonate (5,5-dimethyl-1,3-dioxan-2-one) (6) prepared in this manner has high purity (99.5%) and can be anionically polymerized to polycarbonates with mol wt of 35,000 (39). 

Selenophene, 2,5-diamino-3,4-dicyano-synthesis, 4, 119, 964 Selenophene, 2,4-diaryl-synthesis, 4, 967 UV spectra, 4, 941 Selenophene, 2,5-diaryl-synthesis, 4, 967, 969 UV spectra, 4, 941 Selenophene, 2,5-dichloro-metallation, 4, 949 Selenophene, dihydro-3-methylene-synthesis, 4, 963 Selenophene, 2,5-dimethoxy-lithiation, 4, 949 Selenophene, 2,4-dimethyl-... 

The procedure described is an example of a more general synthetic method for the direct conversion of ketones into cyanides. " The reaction has been carried out successfully with acyclic and cyclic aliphatic ketones, including numerous steroidal ketones and aryl-alkyl ketones. The conversion of diaryl or highly hindered ketones such as camphor and )3,j8-dimethyl-a-tetralone requires the use of a more polar solvent. The dimethoxyethane used in the present procedure should be replaced by dimethyl sulfoxide. ... 

Reduction of 3,5,5-tris-aryl-2(5// )-furanones 115 (R, R, R = aryl) with dimethyl sulfide-borane led to the formation of the 2,5-dihydrofurans 116 in high yields. However, in the case of 3,4-diaryl-2(5//)-furanones 115 (R, R = aryl R = H or r = H R, R = aryl), the reduction led to a complicated mixture of products of which only the diarylfurans 117 could be characterized (Scheme 36) (88S68). It was concluded that the smooth conversion of the tris-aryl-2(5//)-furanones to the corresponding furan derivatives with the dimethylsulfide-borane complex in high yields could be due to the presence of bulky aryl substituents which prevent addition reaction across the double bond (88S68). 

The effects of substituents have been determined in the cleavage of diaryl-mercury compounds by hydrogen chloride in dimethyl sulphoxide-dioxan at 32 °C. Rates were measured within the temperature range 12.8-75.0 °C, though over a range of not more than 18 °C for each compound611 (Table 184). The... 

Dimethyl a-disulfone forms the fragments shown in equation (35) under electron impact at 70 eV. The fragmentation processes are closely related to the thermal484 and photochemical48 results reported for diaryl a-disulfones. In contrast to MeS02SMe, MeS02S02Me shows no indication of the formation of MeS(OH)2 + 48b. 

Bis- 3-(bzw.4)-[2,2-dimethyl-2-(2-hydroxy-propyl)-1 -dehydro-hydrazinocarbonyl]-phenyl - 687 Bis-[2-methy]-phenyl]- 538 -bis-phosphonsaure-diester 523 Bis-[trifluormethy]]- 538 tert.-Butyl-( 1-hydroperoxy-cyclopentyl)- 571 tert.-Butyl-( 1 -hydroxy-cyclopentyl)- 571 (4-Chlor-phenyl)-(2-nitro-phenyl)- 693 (4-Chlor-phenylthio)-(4-nitro-phenyl)- 700 [Cyclohexen-(l)-yl]-phenyl- 368 Diaryl- 550, 552, 558, 567 Diphenyl-... 

Ordinary ketones are generally much more difficult to cleave than trihalo ketones or p-diketones, because the carbanion intermediates in these cases are more stable than simple carbanions. However, nonenolizable ketones can be cleaved by treatment with a 10 3 mixture of t-BuOK—H2O in an aprotic solvent such as ether, dimethyl sulfoxide, 1,2-dimethoxyethane (glyme), and so on, or with sohd t-BuOK in the absence of a solvent. When the reaction is applied to monosubstituted diaryl ketones, that aryl group preferentially cleaves that comes off as the more stable carbanion, except that aryl groups substituted in the ortho position are more readily cleaved than otherwise because of the steric effect (relief of stain). In certain cases, cyclic ketones can be cleaved by base treatment, even if they are enolizable. " OS VI, 625. See also OS VH, 297. 

The sterically unbiased dienes, 5,5-diarylcyclopentadienes 90, wherein one of the aryl groups is substituted with NO, Cl and NCCHj), were designed and synthesized by Halterman et al. [163] Diels-Alder cycloaddition with dimethyl acetylenedicarbo-xylate at reflux (81 °C) was studied syn addition (with respect to the substituted benzene) was favored in the case of the nitro group (90a, X = NO ) (syrr.anti = 68 32), whereas anti addition (with respect to the substituted benzene) is favored in the case of dimethylamino group (90b, X = N(CH3)2) (syn anti = 38 62). The facial preference is consistent with those observed in the hydride reduction of the relevant 2,2-diaryl-cyclopentanones 8 with sodium borohydride, and in dihydroxylation of 3,3-diarylcy-clopentenes 43 with osmium trioxide. In the present system, the interaction of the diene n orbital with the o bonds at the (3 positions (at the 5 position) is symmetry-forbidden. Thus, the major product results from approach of the dienophile from the face opposite the better n electron donor at the (3 positions, in a similar manner to spiro conjugation. Unsymmetrization of the diene % orbitals is inherent in 90, and this is consistent with the observed facial selectivities (91 for 90a 92 for 90b). 

Directed lithiation of aromatic compounds is a reaction of broad scope and considerable synthetic utility. The metalation of arenesulfonyl systems was first observed by Gilman and Webb and by Truce and Amos who reported that diphenyl sulfone is easily metalated at an orf/io-position by butyllithium. Subsequently, in 1958, Truce and coworkers discovered that metalation of mesityl phenyl sulfone (110) occurred entirely at an orf/io-methyl group and not at a ring carbon, as expected. Furthermore, refluxing an ether solution of the lithiated species resulted in a novel and unusual variation of the Smiles rearrangement and formation of 2-benzyl-4,6-dimethyl-benzenesulfinic acid (111) in almost quatitative yield (equation 78). Several other o-methyl diaryl sulfones have also been shown to rearrange to o-benzylbenzenesulfinic acids when heated in ether solution with... 

For species 11 we will use the intrinsic barrier for hydroxide addition to trimethyl phosphate, G = 19 (calculated using rate and equilibrium data from reference 100) and assume the same value for the attack of hydroxide at sulfur on dimethyl sulfate. This (nonobservable) rate will be estimated using a Brpnsted type plot from the rate constants for diaryl sulfates (diphenyl sulfate,and bis p-nitrophenyl sulfate), estimated from the rate for phenyl dinitrophenyl sulfate,assuming equal contributions for the two nitro groups. This gives ftg = 0.95, and thus for dimethyl sulfate log k = 11.3... 

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... 

Thermal 1,2-diaryl rearrangement in disilenes was first demonstrated for tetraaryldisilene 13, which was found to give a mixture of (Z)- and (E)-S.64 More recently, kinetic data, as well as the scope and limitation of the 1,2-rearrangement, have been reported (Scheme 8).11,12 Similar rearrangement was also observed for 2,6-dimethyl-4-t-butylphenyl derivative 14 to give a mixture of (Z)- and ( )-6, but not for disilenes Mes(R) Si=SiMes(R) (3 R = /-Bu 7 R = N(SiMe3)2 8 R = Tip). These re-... 

The carbene moieties of methyl diazoacetate 353), dimethyl diazomalonate 3S3) and diazomethane 3541 have been inserted into the Se—Se bond of diaryl diselenides. 

When a commercially available C2-symmetric l,4 3,6-dianhydro-D-mannite 29 is chosen as the backbone, reaction of this diol compound with chlorophos-phoric acid diaryl ester gives a series of phosphorate ligands 30. These were tested using the asymmetric hydrogenation of dimethyl itaconate as a model... 

Diaryl benzenephosphonothioates (>80%) and 0,0-dimethyl O-aryl phos-phothionates have been synthesized under mild conditions from the reaction of phenols under basic two-phase conditions with benzenephosphonothioic dichloride and dimethyl phosphorochloridothionate, respectively [9, 10]. The reaction with the phosphorochloridothionate requires the catalytic effect of both tetra- -butylammo-nium bromide and A-methylimidazole for the rate to be sufficiently enhanced to make it a viable route to the ester [10]. 

Diorganyl tellurides have low molecular mass and are colourless or yellowish liquids with an unpleasant and penetrating odour. Dimethyl teUuride is a metabolite of tellurium and tellurium compounds in a variety of living organisms, including humans. Higher dialkyl tellurides and most diaryl tellurides are solids with low melting points (diphenyl telluride is a liquid). 

For a series of 2,2-diaryl AT-oxides Vc=n and Vn q have been correlated respectively with bands in the ranges 1560-1619 and 1120-1180 cm". Both symmetric (1520cm ) and antisymmetric (1570, 1590cm" ) C=N modes have been assigned in two isomeric 2,2-dimethyl N-oxides the latter were inactive in the laser Raman spectra. ... 

Laser flash photolysis (LFP) studies have been carried out on the generation of N,C-diaryl nitrile imines from sydnones and from tetrazoles in solution at 77 K. They were found to have hfetimes of milliseconds and were quenched by dimethyl acetylenedicarboxylate (DMAD) (A q=5-9 x 10 M s ) and by carboxyhc acids (feq= lO -lO s ) (13). The strong dependence of v ax on the nature of the aromatic substituents in N,C-diaryl nitrile imines was interpreted by a hnear free energy relationship as due to intramolecular charge transfer (14). 

N-Alkyl-aniline und Diphenylamin gehen mit 1,4-Dioxo- und mit 2,6-Dimethyl-l, 4-dioxo-cyclohexan eine saure-katalysierte Kondensation ein, die zu Alkyl-diaryl- bzw. zu Tri-aryl-aminen fuhrt diese Reaktion stellt insgesamt eine N-Arylierung dar2. 

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