1.2- Diphenylethane preparation

Tliere is only one report concerning the reaction of A -(l-chloroalkyl)-pyridinium chlorides with secondary diamines (92BSB233). 2-Substituted 1,3-dimethyl- and 1,3-diphenyl-imidazolidines 79 have been prepared (75-95% yields) starting from either -dimethyl- or A, A -diphenylethane-1,2-diamines, respectively (Scheme 25). Reactions are particularly fast for the preparation of the 1,3-dimethylimidazolidines. Reaction times as short as 5 min have been claimed. 

Racemic and meso 2,3-diphenyldihydrodiazepines have been prepared starting from racemic and meso 1,2-diamino-1,2-diphenylethane (77TL2709). 

Copolymers were photochemically prepared with UV light using 2,2-dimethoxy-l,2-diphenylethane-l-one as the photoinitiator. 

It has been shown that 1,1-diphenylethene does not react with preformed lead(IV) fluoride, prepared by the reaction of lead(II) fluoride and elemental fluorine,20 whereas treatment with lead diacetate difluoride19,20 converts 1,1-diphenylethene into l,l-difluoro-l,2-diphenylethane (2), due to a radical rearrangement. Dimer 3 is also isolated.21... 

Diphenylacetaldehyde has been prepared by the isomerization of 1,2-dihydroxy-1,2-diphenylethane either thermally 4 or in the presence of sulfuric acid 5 7, oxalic acid,8 or acetic anhydride.9 The aldehyde has also been produced by the reaction of 2,2-diphcnyl-2-hydroxyethyl ether with sulfuric acid78 or oxalic acid,s 10 by the reaction of hydrochloric acid with 2-amino-1,1-diphenylothano]," by the reaction of hydrobromic acid with 2-diethylamino-l, 1-diphcnylelhanol,12 by the hydrolysis of /3,/3-diplienylvinyl ethyl ether,13 by the thermal rearrangement of... 

Commercially, the best way to prepare 1,1-DPE is probably to react styrene and benzene with one another and then to dehydrogenate the resulting 1,1-diphenylethane to 1,1-diphenylethylene. This has been developed to the pilot plant stage in BASF [7]. 

Preparative Methods both the (4R,5R) and (4S.5S) compounds are readily available by condensation of optically active l,2-bis(methylamino)-l,2-diphenylethanes with methyl ( )-4-0X0-2-butenoate. ... 

Another chiral bimetallic Lewis acid 56 prepared from phenylboronic acid and l-tartaric acid by azeotropic distillation selects 1,6-diaminohexane over 1,2-diami-noethane by using two boron centers and two carbonyl oxygens (Fig. 22) [64b]. In the interaction with l,2-diamino-l,2-diphenylethane, 56 chooses a different complexation pattern by recognizing the chirality of the amines. In both examples the carbonyl groups in 56 play essential roles as Lewis basic sites. 

Heating stilbene with benzoyl peroxide and iodine in carbon tetrachloride at 80 °C for 48 h gives an 83% yield of the dibenzoyl ester of hydrobenzoin (l,2-dibenzoxy-l,2-diphenylethane) [230]. Esters of vicinal diols are intermediates in the preparation of diols by the Prevost and the Woodward methods (equation 78). 

Anodic oxidation of l,2-bis(trimethylsilyl)-l,2-diphenylethane in methanol afforded 1,2-dimethoxy-1,2-diphenylethane d, l/meso 10) [380]. y-Acyloxyvinylstannanes undergo copper mediated anodic homocoupling to afford 1,3-dienes without isomerization. Thus, optically active 1,3-dienes were prepared anodically from optically active alkenylstannanes [381]. 

The preparation of benzyllithium from benzyl halides and alkyllithiums is not feasible because the benzyllithium initially formed reacts with the starting benzyl halides, producing 1,2-diphenylethane. Metalation of toluene with n-BuLi in the presence of TMEDA at 30 °C results in a 92 8 ratio of benzyllithium and ring metalated products. Metalation of toluene with n-BuLi in the presence of potassium rert-butoxide, and treatment of the resultant organopotassium compound with lithium bromide, affords pure benzyllithium in 89% yield. Alternatively, benzyllithiums are accessible by cleavage of alkyl benzyl ethers with lithium metal. " ... 

W-(p-toluenesulfinyl)bomane-10,2-sultam in the (/Jj-form delivers the sulfinyl group to various nucleophiles. Thus, chiral vinyl sulfoxide and p-toluenesulfinimines are readily prepared. Enantiopure ketones can be obtained from l,2-bis(benzenesulfonyl)alkenes via acetal formation with chiral diols such as (+)-l,2-diphenylethane-l,2-diol. ... 

Corey and co-workers developed the highly enantioselective allylboron reagent 198 [127], whose chiral 1,2-diamino-1,2-diphenylethane (stein) auxiliary [254] serves as the source of asymmetry. In an extension of this methodology, Williams et al. have demonstrated the utility of the bromoborane 332 for the preparation of synthetically complex allylborane reagents [255] and have applied this methodology in two natural product syntheses [256, 257] (see below). 

Thiosemicarbazides bearing a bulky alkyl substituent in the 4-position behave similarly. Thus, in reactions of 4-(2,2,4-trimethylpent-4-yl), 4-terZ-butyl- or 4-isopropylthiosemicarbazide with 2-bromo-l,2-diphenylethan-l-one, 2-bromo-l-phenylpropan-l-one, or phenacyl bromides, the 2-(alkylimino)-4-aryl-2,3-dihydrothiazol-3-amines are always formed as side products and, in the case of 4-isopropyllhiosemicarbazide, additional, small amounts of the corresponding 2-hydrazono-3-isopropyl-4-phenyl-2,3-dihydrothiazole are also obtained.10 These side products can be isolated preparatively by chromatographic workup on Sephadex LH-20.43... 

Phenyl- and 5-aryl-2-benzyl-6//-l,3,4-thiadiazincs 8 (R3 = Ph, Bn) are prepared by condensation of thiobenzohydrazide or phenylthioacetic acid hydrazide with a-halocarbonyl compounds.10, 50 Under appropriate conditions it is also possible to isolate the primarily formed 4,5-dihydro-6//-1,3,4-thiadiazin-5-ol intermediates 7a-h. For this purpose, the thiohydrazide is added to an equimolar amount of sodium ethoxide solution, then at — 25 °C an ethanolic solution of the respective phenacyl bromide, 2-bromo-l,2-diphenylethan-l-one, 2-bromo-l-phenylpropan-l-one, or 2-bromo-l-phenylbutan-l-one is added. The 4,5-dihydro-6//-l,3,4-thiadiazin-5-ols 7 separate as colorless precipitates. They undergo partial dehydration at room temperature to the 2-phenyl- or 2-benzyl-6//-l, 3,4-thiadiazines 8 on heating for about 5-7 minutes in ethanol or chloroform, the dehydration is complete. 

Some alkanoic and alkenoic acids derived from biphenyl, stilbene and diphenylethane were reported to have potential antirheumatic and hypo-cholesterolaemic properties. Some of these compounds were later investigated by Milla and Grumelli for anti-inflammatory activity the only compound which showed activity was 3-(4-biphenylyl) acrylic acid, p-PhCgH4 GH = CH-CO-OH. Some of the alkylamine esters of this acid prepared by Carissimi , and the acid itself, were then examined for antiinflammatory activity in dextran oedema of the rat-foot, experimental granuloma in the rat, and synovial permeability in the rabbit, and for their ability to modify the reactions of subcutaneous connective tissue in mice. 

In some cases oxidative union of two carbon atoms can be used for preparation of diphenylethane derivatives House295 describes a simple synthesis of 4,4 -dinitrobibenzyl from p-nitrotoluene ... 

Diphenylmethane, (C6H5)2CH2, is best prepared from benzyl chloride, C6H5CH2CI, and benzene by the Friedel and Crafts synthesis. It melts at 26° and boils at 262°. Homo-logues of this compound can be prepared from aldehydes and aromatic hydrocarbons by the action of sulphuric acid. Thus, aldehyde or acetal and benzene when shaken with sulphuric acid give diphenyl-methyl-methane (unsymmetrical diphenylethane) ... 

The method of preparing unsymmetrical diphenylethane (C6H6)2-CH.CH3, was mentioned under diphenylmethane. The symmetrical compound melts at 53° and boils at 277° unsymmetrical diphenylethane is a liquid which boils at 286°. Oxidizing agents convert the former into benzoic acid, and the latter into benzophenone. 

The Corey-Winter reaction proceeds with complete stereospecificity by a syn elimination pathway, allowing the stereospecific synthesis of alkenes. Thus, anti-1,2-diphenylethane-1,2-diol was converted into cis -stilbene (2.45), whereas the corresponding syn-diol gave irans -stilbene. The strained fi-cyclooctene was prepared from the Z-isomer using this procedure (2.46). An alternative stereospecific route to alkenes proceeds from the diol with ethyl orthoformate or WA(-dimethylformanude dimethyl acetal, or by conversion of the diol to a 2-phenyl-1,3-dioxolane and treatment with an organolithium reagent to promote proton abstraction at C-2 and... 

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