1,2-diaryl ethanols

The Hammett correlation of the acid-catalyzed dehydration of 1,2-diaryl ethanols has been studied. The correlation resulting from substitution on both the 1- and 2-aryl rings is log k = -3.78(CTi-1-0.23aAr ) - 3.18. Rationalize the form of this correlation equation. What information does it give about the involvement of the Ar ring in the rate-determining step of the reaction ... 

Weitere Beispiele fur diese Art der Mitsunobu-Reaktion sind die Umwandlung eines 2,2-Diaryl-ethanols in 2-Amino-I-(4-benzyloxy-phenyl)-l-(2-benzyloxy-3-methoxy-phenyl)-ethan2 und die Umwandlung von 5-Hydroxy-2-methyl-l-hexen-3-in in 5-Phthalimido-2-methyl-l-hexen-3-in, das (wie oben formuliert) in 5-Amino-4-ethyl-l-hydroxy-2-methyl-2,3-hexadien ubergefuhrt werden kann3 ... 

Oxidations of l-(4-methoxyphenyl)-2-(4-substituted phenyl)ethanols, (6), [identical to alcohols (4a) to (4e) except for methylation of the 4-OH group] were also studied with cerium(IV) as the catalyst (Fisher, T. H., et al., J. Org. Chem., in press). To determine if oxidation occurs by electron abstraction from the benzylic hydroxyl or the aromatic ring, a competitive oxidation procedure was examined on the diaryl ethanol 6a and its methyl ether analog, 1-methoxy-l-(4-methoxyphenyl)-2-phenylethane, (7), (Fisher, T. H., et al., J. Org. Chem., in press). 

Diaryl ditellurides, which are more important as synthetic intermediates, are sohds, highly soluble in solvents such as petroleum ether, benzene, chloroform, ether, and tetrahy-drofuran (THF), but are less soluble in methanol and ethanol. 

Aryltellurium trichlorides are highly soluble in methanol and ethanol but less soluble in benzene. Diaryltellurium dichlorides exhibit inverse solubilities, being more soluble in benzene than in methanol or ethanol. These properties allow an easy separation of diaryl tellurides from diaryl ditellurides (frequently formed as by-products in the preparation of tellurides) the mixture is treated with SOjClj and the obtained mixed di- and trichlorides are separated by the appropriate solvents, and reduced back into the pure tellurides and ditellurides. 

Sodium telluride and sodinm 0,0-diethyl phosphorotellurolate, prepared respectively by the Te/NaBH4DMF method and by the reaction of elemental tellurium with NaH and 0,0-diethyl phosphate in ethanol, react with arenediazonium fluoroborates, giving good yields of diaryl tellurides. ... 

Dialkyl and diaryl sulfoxides were reduced (deoxygenated) to sulfides by several methods. As a little surprise sulfides were obtained from sulfoxides by catalytic hydrogenation over 5% palladium on charcoal in ethanol at 80-90° and 65-90 atm in yields of 59-99% [684. In the case of p-tolyl -styryl sulfoxide deoxygenation was achieved even without reduction of the double bond giving 66% of p-tolyl -styryl sulfide and only 16% of p-tolyl -phenyl-ethyl sulfide [684],... 

Alkylation of 2-amino-5-(alkyl, aryl, hetaryl)-l,3,4-oxadiazoles is said to occur at the ring N atom (N-3) (94HOU526), but this report remains doubtful. In addition, as others have pointed out, the very low basicity of imidazo[2,l-b][l,3,4]oxadiazoles precludes the isolation of hydrohalides of type 20. 2,6-Diaryl-imidazo[2,l-ft][l,3,4]oxadiazoles 22 can be obtained directly by treatment of 2-amino-5-aryl-l,3,4-oxadiazoles 21 with phenacyl-bromides in ethanol [reflux in a water bath at 70°C ( ) for 5 h] (84MI1). 

Substitution of the halogen in 387 and 388 by nucleophiles has also been reported (81M245 83AP697), as has the cyclization of 389 into 390 (83G219). Ethyl l,5-diaryl-3-trifluoromethyl-4-oxopyrazolo[3,4-c/] pyridazin-7-ylacetate afforded bicyclic 5(5-oxopyrazol-3-yl)pyrazolines upon treatment with ethanolic sodium ethoxide (88JHC134). 

Butler and co-workers studied the quatemisation of 3,5-diaryl-l,2,4-thiadiazoles 77 with trimethylsilylmethyl triflate at 40 °C and observed reaction at N-2 to give salt 78. Desilyation of 78 with caesium fluoride resulted in ring expansion to 2ff-l,3,5-thiadiazines 79 which on heating in ethanolic sodium ethoxide gave 2,4-... 

Azapteridines (pyrimido[4,5- ]-l,2,4-triazines) are stable solids with good thermal stability. Thus, the 3,6-diaryl-pyrimido[5,4- ]-l,2,4-triazines 18 (R = Ar) show melting points in excess of 350°C without decomposition after recrystallization from ethanol. The corresponding 6-unsubstituted system 18 (R = H) shows decomposition at 325°C <2003CCC965>. These systems are soluble in chloroform. 

Diaryl-2-cthoxy-2,3-dihydro-l, 3,4-oxadiazole lOmmol 2-Aryl-1-benzoyl-hydrazin erhitzt man mit 20-30 mmol OrthocarbonsSure-triester unter Abdestillation des gebildeten Ethanols. Das Produkt kristallisiert beim Abkiihlen odcr nach teilweisem Abdestillieren dcs Orthocarbonsaure-triesters i. Vak. ans. 

The 1,1-diaryl-2,2-difluorocthane derivative (2.2g) and 2% ethanolic KOH (60 mL) were heated under reflux for 2.5 h. Then, the alcohol was evaporated under reduced pressure and the residue repeatedly extracted with Et20. The combined ethereal solutions were washed with H20 and dried (MgS04). The Et,() was evaporated, and the colorless oil thus obtained distilled under reduced pressure. Recrystallization (MeOH) gave the ethene derivatives summarized in Table 5. 

The synthesis of diaryl-thiazolotriazepines 62 from the reaction of l,2,4-triazepine-3-thiones 63 (1.8 mmol) with 2-haloketones 64 (6.25 mmol) in ethanol under reflux for 2h was described <1999T5909> with the goal of creating new immunomodulating agents (Scheme 5). The starting triazepines were prepared by the addition of thiocyanic acid 65 to the chalcones 66 according to an already known method, followed by reaction of the intermediate 67 with hydrazine. 

The application of arylpyruvic acids 256 in place of pyruvic acid in three-component reactions leads to dramatic changes in the direction of the process. Refluxing of starting compounds for 3 hours of irradiating with microwave at 170°C for 20 minutes in acetic acid yielded 3-hydroxy-4,5-diaryl-l-azolyl-2,5-dihydro-li/-2-pyrrolones 258 [203] (Scheme 3.73). Under ultrasonic irradiation in ethanol with the addition of catalytic amounts of hydrochloric acid or in acetic acid, the reaction proceeds in a different direction with the formation of pyrimidinecarboxylic acids 259. In the case of pyruvic acid the course of the three-component reaction does not so drastically depend on the activation method or solvent type as well as from temperature mode [202]. 

Aryl-1,2-dithiolium salts are attacked by triethylamine in aqueous ethanol. Apparently one molecule of salt is first attacked by water, with loss of sulfur. The hypothetical 3-aryl-3-thioxopropanal (or its corresponding enol) would then react on another molecule of dithiolium salt to give a 2,5-diaryl-l,6,6a IV-trithiapentalene-3-carbaldehyde (Scheme 12).62... 

In contrast, a Markovnikov addition of water was reported in the irradiation of a variety of o-hydroxystyrenes, again in aqueous acetonitrile, with the formation of 2-(2-hydroxyphenyl)ethanols. In this case, an intramolecular proton transfer from the excited state of the styrene was envisaged as the first step of the reaction [51]. A similar mechanism was postulated in the photohydratation of m-hydroxy-1,1 -diaryl alkenes that gave the corresponding 1,1-diarylethanols, although direct protonation of the P-carbon by water competed in some cases [52]. 

Diphenyl- and di-p -tolyl-1,2,4-selenadiazoles (163) are prepared by iodine cyclooxidation of the corresponding arylselenoamides (Scheme 67) (04CB2550). Some diaryl-1,2,4-selenadiazoles including 3,5-di(2-thienyl)-l,2,4-selenadiazole (164) are prepared by the same method (78S768). Diaryl-1,2,4-selenadiazoles are crystalline compounds. Compound (163b) is reduced by sodium in ethanol to give p-tolylmethylamine. 

Tellurium tetrachloride and arenethiols in ethanol at — 8° produce bis[arylthio] tellurium compounds and diaryl disulfanes. Tetrakis[organothio] tellurium derivatives are likely intermediates in these reactions1. 

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