Bis 4-bromophenyl

Bromination of 2,3-diphenylcyclopropenone with two molar equivalents of Ai-bromosuc-cinimide in 80% sulfuric acid at 25 to 60 C afforded 2,3-bis(3-bromophenyl)cyclopropenone. ... 

This category of primary synthesis is extremely rare in the quinoxaline series, although a few examples have been reported in recent literature. Thus a mixture of neat 1,2-benzenediamine (331) and an excess of p-bromobenzaldehyde heated at 350°C for 5 min afforded (with aerial oxidation ) 2,3-bis(p-bromophenyl) quinoxaline (332) in 50% yield " " and analogs were made similarly but usually in poor to mediocre yield after separation from byproducts." " In addition, an... 

Note Both direct and indirect alkanelyses are illustrated in these examples. 2,3-Bis(p-bromophenyl)quinoxaline (91) with phenylacetylene (2 equiv) gave 2,3-bis[p-(phenylethynyl)phenyl]quinoxaline (92) (PhsP, Cul, EtsN, AcN Me2, 20°C, A, 15 min then (Ph3P)2PdCl2 i, SOX, 10 h 20%). ... 

Preparation of 2-bromo-3-(p-tolyl)propene (typical procedure) A three-necked, 50 mL flask equipped with an argon inleL a rubber septum and an internal thermometer was charged with bis(p-bromophenyl)ditelluride (1.7 g, 3.0 mmol, 1 equiv) and Ni(acac)2 (77 mg, 0.3 mmol, 10 mol%). The reaction mixture was cooled to -40°C and THF (6 mL) was added. It was further cooled to -78°C and Et2Zn (1.5 mL, 15 mmol, 5 equiv) was slowly added via syringe. The reaction was allowed to warm to room temperature and was stirred for 6 h. Meanwhile, a mixture of copper cyanide (2.68 g, 23 mmol) and lithium chloride (2.54 g, 60 mmol) was dried under vacuum (130°C, 2 h) and dissolved in THF (10 mL). This solution was added to the reaction mixture at -60°C, followed by 2,3-dibro-mopropene (6.0 g, 30 mmol, 10 equiv). The reaction mixture was warmed up to room temperature and worked up as usual. The crude oil obtained after evaporation of the solvents was purified by flash chromatography (hexanes), affording the product (1.45 g, 5.2 mmol, 88% yield) as a colourless oil. 

Telluraxanthene Bis(2-bromophenyl)methane (3.33 g, 1.02 mmol) is dissolved in 300 tuL of absolute diethyl ether and, under dry nitrogen, 22 mL (36.1 mmol) of a 15% solution of n-butyllithium in hexane are added dropwise. The mixture is heated under reflux for 0.5 h, cooled to 20°C and 1.8 g (14.1 mmol) of finely powdered tellurium are added. The resultant mixture is heated under reflux for 2 h and then poured into ice/water. The mixture is extracted with chloroform, the extract is filtered and the solvent is evaporated in a rotatory evaporator at 20°C under aspirator vacuum. The residue is recrystallized from diethyl ether/petroleum ether after addition of activated charcoal. Yield 1.42 g (47%) m.p. 151°C. 

Primary alcohols were oxidised to aldehydes and (less readily) secondary alcohols to ketones by Ru(N0)Cl(salen = )/03//UV (incandescent or halogen lamp), hi competitive experiments between 1- and 2-decanol or benzyl alcohols only the primary alcohol was oxidised [827]. With Ru(NO)Cl(salen )/(Cl2pyNO) or TMPNO or Oj/C H /UV (TMPNO=tetra-methylpyridine-iV,iV -oxide) racemic secondary alcohols were asymmetrically oxidised to ketones [828]. A Ru(NO)(salen " ) complex was used as Ru(N0)Cl(salen " )/02/UV/CgH3Cl to oxidise racemic secondary alcohols to the ketones in the presence of l,3-bis(p-bromophenyl)propane-l,3-dione e.e. of 55-99% were achieved [829], Chiral Ru(NO)Cl(salen ) complexes were made... 

Quinoxaline /V-oxides undergo rearrangements when UV-irradiated. 2,3-Diphenylquinoxaline 1-oxide (224) was originally thought to rearrange to the oxazirino[2,3-a]quinoxaline (225).225 However, subsequently the product was found to be 2,4-diphenyl-3,l,5-benz-oxadiazepine (226).226 This reassignment was supported by NMR spectroscopy, and oxadiazepine formation on irradiation of 2,3-bis(4-bromophenyl)quinoxaline 1-oxide was confirmed by X-ray crystallography.227... 

Both 3,5-dibromo-2,4,4,6-tetraphenyl-47/-thiopyran and 2,6-bis(4-bromophenyl)-4,4-diphenyl-4/7-thiopyran are good substrates for the synthesis of highly substituted 477-thiopyrans through reaction with various electrophilic and nucleophilic species (Scheme 76) <1998CCC662>. 

Umeda and Yokoyama (1997) measured photogeneration efficiencies of single- and dual-layer photoreceptors prepared with 4,4 -[(9,10-dihydro-9,10-dioxo-2,6-anthracenediyl)bis(azo)]bis[N-(3-bromophenyl)-3-hydroxy-2-naphth-alenecaiboxamide] (ABHN) (Hashimoto, 1985) and 4,4 -[l,4-phenylene-bis (2,l-ethenediyl-4,l-phenyleneazo)]bis[N-(2,4-dimethylphenyl)-3-hydroxy-2-na-phthalenecarboxamide] (PDHN) (Sasaki et al., 1980). For the dual-layer configuration, the transport layer contained MAPS. Single-layer photoreceptors... 

A solution of benzamidine hydrochloride dihydrate (48 g, 0.25 mol) in water (100 ml) is added to a solution of a-bromopropiophenone (53 g, 0.25 mol) in chloroform (250 ml) to form a two-phase mixture. While stirring vigorously at room temperature, a solution of KOH (28 g, 0.5 mol) in water (100 ml) is added dropwise, then heated to boiling and refluxed (3-4h). The chloroform phase is then separated from the hot aqueous phase and cooled. Tlie ciwstalline material which separates is washed with benzene, then with diethyl ether to give the above product (which may separate as an oil, but which solidifies gradually on addition of benzene). Ilie yield is in the range 26-32 g (45-55%), m.p. 214-215°C. Similarly prepared are 4-methyl-2,5-bis-(m-nitrophenyI)-(39%), 4-methyl-2,5-bis-(m-bromophenyl)- (40%), and 4-methyl-2,5-bis-(p-nitrophenyl)imidazolcs (64%). 

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