Aryl chlorides arylation

Sandmeyer reaction (Section 22 17) Reaction of an aryl dia zonium ion with CuCl CuBr or CuCN to give respec tively an aryl chloride aryl bromide or aryl cyanide (nitrile)... 

The isomerizations have also proven to be very useful in the synthesis of a series of 1,3-diarylallenes [49-55], even tolerating other functional groups such as aryl chlorides, aryl bromides [56-58] and vinyl bromides [59]. Mixed systems with an alkene on one side and an arene on the other could also be prepared [41, 60], as well as products with two olefinic substituents [61] or bisallenes [62-64],... 

Aryl chlorides Aryl chlorides will substitute alkenes only under very special conditions, and then catalyst turnover numbers are generally not very high. Palladium on charcoal in the presence of triethylphos-phine catalyzes the reaction of chlorobenzene with styrene,58 but the catalyst becomes inactive after one use.59 Examples employing an activated aryl chloride and highly reactive alkenes, such as acrylonitrile, with a palladium acetate-triphenylphosphine catalyst in DMF solution at ISO C with sodium acetate as base react to the extent of only 51% or less.60 Similar results have been reported for the combination of chlorobenzene with styrene in DMF-water at 130 C, using sodium acetate as the base and palladium acetate-diphos as a catalyst.61 Most recently, a method for reacting chlorobenzene with activated alkenes has been claimed where, in addition to the usual palladium dibenzilideneacetone-tri-o-tolylphosphine catalyst, nickel bromide and sodium iodide are added. It is proposed that an equilibrium concentration of iodobenzene is formed from the chlorobenzene-sodium iodide-nickel bromide catalyst and the iodoben-zene then reacts in the palladium-catalyzed alkene substitution. Moderate to good yields were reported from reactions carried out in DMF solution at 140 C 62... 

Aryl chloride Aryl iodide Aryl selenic acid Aryl sulfonic acid Azide... 

Replacement of the Diazonium Group by Chloride, Bromide, and Cyanide The Sandmeyer Reaction Copper salts (cuprous salts) have a special affinity for diazonium salts. Cuprous chloride, cuprous bromide, and cuprous cyanide react with arenediazonium salts to give aryl chlorides, aryl bromides, and aryl cyanides. The use of cuprous salts to replace arenediazonium groups is called the Sandmeyer reaction. The Sandmeyer reaction (using cuprous cyanide) is also an excellent method for attaching another carbon substituent to an aromatic ring. 

Cross-couplings. Organosilyl chlorides are reactive coupling partners for aryl chlorides. Arylation and alkenylation are readily achieved. 

Sandmeyer reaction Reaction of an aryl diazonium ion with CuCl, CuBr, or CuCN to give, respectively, an aryl chloride, aryl bromide, or aryl cyanide (nitrile). 

In 2008, Buchwald and colleagues developed an efficient procedure for the carbonylation of aryl chlorides, aryl tosylates and aryl mesylates [202-204]. Under their reaction conditions, carboxylic acid derivatives were prepared in good yields (Scheme 2.23). The advantages of this procedure are (1) l,3-bis(dicyclohexyl-phosphino)propane bis(tetrafluoroborate) as the ligand used is stable and easily available and (2) the reactions were carried out in a reaction tube under 1 bar of CO, avoid the using of autoclave. 

Aryl chlorides are important starting materials in palladium-catalyzed coupling reactions [7]. Compared with the corresponding aryl iodides or aryl bromides, the advantages of aryl chlorides are obviously that they are inexpensive, easy to prepare, stable, etc. The same is true if we compare aryl tosylates or aryl mesylates with their aryl triflates analogs. Even though aryl chlorides, aryl mesylates and aryl acetates have been studied and have succeeded in cross-coupling reactions, their... 

We then examined the reactions of a variety of aiyl halides with aiylboronic acids containing both electron donating and electron attracting substituents, Table VI. As can be seen from the data contained in Table VI, the reaction appears to be insensitive to the substituents on the boronic acid. However, the reaction is most efficient when aryl iodides are used as the co-reactant. In fact the reactivity trend aiyl iodide > aryl bromide > aryl chloride > aryl fluoride parallels the trend observed in Suzuki reactions carried out thermally, both in solution and on alumina. 

It has been observed that reductive elimination can also occur for aryl-Pd-carbene complexes. Such complexes were investigated in mechanistic studies on Heck coupling and catalyst decomposition routes. Reductive elimination products with direct imidazolium-aryl coupling were observed and in one case fully characterized. Such products provide direct evidence of the Heck coupling mechanism and of intermediates in the catalytic cycle. Important mechanistic studies on the oxidative addition of aryl chlorides to a 14-electron Pd(0)(carbene)2 complex have demonstrated that oxidative addition occurs via a dissociative process and this step is probably the rate-determining step in the amination of aryl chlorides. Aryl-carbene reductive coupling was observed in this study of the amination reaction, and directly coupled aryl-imidazolium compounds were isolated. A further study on an (aryl)Pd(carbene) complex has also demonstrated that such complexes undergo facile reductive elimination to form aryl-imidazolium salt. ... 

Numerous ligands have been applied successfully to the Heck reaction, including phosphines, phosphites, palladacycles and carbenes. Of the reported ligands however, several stand out for their high activity and substrate scope. Perhaps the greatest advance of this chemistry was the discovery of ligands which enable the Heck reaction of aryl chlorides. Aryl... 

Hydrogen autotransfer has been shown to tolerate a wide range of functional groups, including esters, ethers, tertiary amines, aryl chlorides, aryl bromides, aryl iodides, ketals, nitroarenes, nitriles, and oxetanes. Notably, Williams reported a series of amine alleviations with alcohols in the presence of boronic esters which could be present in either the alcohol or amine starting material (Scheme 12.9). °... 

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