Bromoiodobenzene

Bromoiodobenzene, AF56 a-Bromo-4-iodotoluene, AJ34 Bromomaleic acid, AC35 Bromomethane, AAl8... 

Common Name 4-Bromoiodobenzene Synonym 4-bromo-l-iodobenzene Chemical Name ... 

Sodium benzenetellurolate and 4-bromoiodobenzene irradiated in liquid ammonia for 220 min with a 250 W UV lamp with a maximal emission at 350 nm, produced phenyl 4-phenyltellurophenyl tellurium (30% yield) as the main product, and diphenyl tellurium (20%) and 4-bromophenyl phenyl tellurium (7%) as the by-products2. 

Phenyl 4-(Phenyltelluro)phenyl Tellurium2 A 500-ml, three-necked, round-bottom flask is fitted with a cold-finger condenser charged with dry ice/ethanol, a nitrogen inlet, and a magnetic stirrer. 250 ml of liquid ammonia are condensed into the flask, 1.6 g (4 mmol) of diphenyl ditellurium and then pieces of sodium are added until the blue color persists. A very small amount of diphenyl ditellurium is added to discharge the blue color followed by 1.13 g (4 mmol) of 4-bromoiodobenzene, and the mixture is irradiated for 220 min. The reaction is quenched by addition of 10 ml of distilled water, the ammonia is allowed to evaporate, the residue is diluted with 100 ml of water, and the whole is extracted three times with 100 ml of diethyl ether. The extract is dried with anhydrous sodium sulfate, the solvent is distilled off, and the residue is chromatographed on neutral aluminum oxide with petroleum ether as eluent yield 0.58 g (30%) m.p. 88-907... 

Scheme 15.74. Chemoselective Heck coupling of 4-bromoiodobenzene and styrene.

Scheme 36, A and Turnover numbers up to approximately 500,000 were reported for the reaction of iodobenzene with methyl acrylate and an impressive nnmber (about 100,000) was also achieved with bromobenzene and 4-methoxy-bromobenzene. Characteristic featnres of these tridentate PCP catalysts are thermal stability and air stability. A competitive experiment, including 4-bromoiodobenzene, iodobenzene, 4-methyliodoben-zene, and 4-methoxy-iodobenzene with methyl acrylate provided a linear correlation with Hammet cr-valnes, which, however, exhibited a low p valne (1.39). It was concluded that nucleophilic aromatic substitution is not rate determining, bnt a snbsequent step with different electronic requirements, such as alkene insertion, may acconnt for this observation. Chlorobenzene could not be coupled with these catalyst. Very recently, Milstein s group reported new cyclopalladated, phosphine-free imine complexes as catalysts in the Heck arylation reaction (Scheme 36, The new dimeric imine complexes show... 

Martin and coworkers [67] have recently developed a mild organocatalyhic C (sp )-H bond functionalization/C-O bond forming process that provides efficient access to benzolactones 89 (Scheme 21). The authors used 20 mol% of 4-iodotoluene as an organocatalyst in combination with 2.2 equiv. of AcOOH as a terminal oxidant in this intramolecular oxidative coupling reaction. Importantly, the authors successfully extended the methodology to the frmctionalization of the C (sp )-H bond in 90 to obtain diverse benzoxazinone derivatives 91. Interestingly, in this case 4-bromoiodobenzene was found to be the optimal organocatalyst. 

Fig. 7. Plot of log[lCa/fcfc] at 333 K vs. Hammett a constants. Each point represents the average of at least three independent experiments [69 Dan 1]. /, 4-methyliodoben-zene 2, 3-methyliodobenzene S, 4

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