Dihalides reaction with aromatic

Palladium-catalyzed a-arylation of ketones is performed with arylene dihalides and bifunctional aromatic ketones 148 to result in the bond formation at the r/) -a-carbon of the ketone, leading to polyketone 149. The reaction is carried out in the presence of Pd(0) and various phosphines. Several bidentate phosphines and bulky alkylphosphines such as dppf, BINAP, PCys, and P Bu3 are shown to be effective, while PPh3 results in no reaction. Arylene dibromide and diiodide are applicable as the co-monomers. The polymerization reaction is carried out in THE in the presence of NaO Bu at 75 °C under N2, and polymers 149 are isolated in 60-80% yields (M = 7000-15 000). Polyketone 149 is further transformed to conjugated polymer PPV by reduction of the ketone moiety with LiAlH4 followed by dehydration with an acid (Equation (69)). 

Diorgano tellurium dihalides are often the primary products of reactions producing compounds with two tellurium-carbon bonds. Such reactions arc the condensation of tellurium tetrachloride with aromatic compounds (p. 527), the addition of tellurium tetrachloride or organo tellurium trichlorides to carbon-carbon multiple bonds (p. 530, 544), and the alkylation or arylation of organo tellurium trihalides (p. 549). The symmetrical and unsymmetrical diorgano tellurium dihalides are convenient starting materials for the preparation of diorgano tellurium derivatives. 

Unsymmetrical diorganyltellurium dihalides are formed upon condensation of aryltellurium trichlorides with activated aromatic compounds and with ketones. The addition of the trichloride across carbon-carbon double bonds in alkenes, as well as the reaction with aryl(trimethyl)silane, hexaphenyldilead, and aryhnercury chlorides leads to the transfer of the aryl group to the tellurium atom. 

Primary aliphatic479 and aromatic amines480-482 may undergo ring closure on reaction with oc,co-dihalides, affording iV-alkylated and iV-arylated heterocycles, respectively. When the formation of oc,co-diamines is regarded as a side reaction to be avoided, it is best to use equivalent amounts of amine and dihalide together with 1 equivalent of sodium carbonate.482,483... 

Two further methods of preparing organoboron compounds have been the subject of fairly recent detailed study, namely, reaction of boron halides with hydrocarbons and addition of boron hydrides to olefins. For instance, arylboron dihalides are formed when boron trihalides are heated with aromatic hydrocarbons, aluminum chloride, and aluminum powder,217 and phenyl-boron dibromide has been prepared analogously.218 Further, boron halides such as diboron tetrachloride and tetrafluoride add to olefins, yielding bis-(dichloroboryl) and bis(difluoroboryl) compounds 219... 

Aromatic 1,2-dihalides (I, Br) gave only traces of benzyne on gas-phase reaction with alkali metal vapors under microwave or ultrasound excitation. Electroreduction of such... 

PTs can be prepared by involving the aromatic nucleophilic displacement reaction of di(hydroxyphenyl)-1,2,4-triazole monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The reactions are carried out in polar aprotic solvents, such as sulfolane or diphenyl sulfone, using alkaU metal bases, such as potassium carbonate, at elevated temperatures under nitrogen. 

Poly(bis-l,2,4-triazole)s are a class of polymers in which two triazole rings are immediately adjacent. These polymers can be obtained by the reaction of oxalic acid bis-amidrazone with aromatic dicarboxylic acid dihalides or with fumaroyl chloride and subsequent cyclodehydration of the poly(acyl oxamidrazone)s. The process is shown in Figure 9.3. 

PTs can be prepared by involving the aromatic nucleophilic displacement reaction of di(hydro-xyphenyl)-1,2,4-triazole monomers with activated aromatic dihalides or activated aromatic dinitro... 

The synthesis of conjugated polymers containing ferrocene units in their backbones has received much attention in recent years (78-81). Bochmann and co-workers have described the synthesis of ferrocene-based polymers via palladium-catalyzed coupling reactions of dihalide or divinyl functionalized ferrocene monomers with aromatic spacers (37) (78). 

As previously noted, the reaction of alcohol (both aromatic and aliphatic) containing reactants with mono- and dihaloorgano-stannanes to form tin ethers is well known (for Instance 2-5) and the reaction with sucrose with organostannane dihalides should proceed in an analogous manner. 

Reaction of Aromatic Aldehydes with Organoboron Dihalides. 

A consequence of the reaction is that it is possible to produce a range of polymers by reacting bisphenates with appropriately activated aromatic dihalides. In the case when the dihalide is activated by the presence of a sulphone —SO,— group the polymers may be referred to as polysulphones. The Amoco materials are prepared in this way. 

Diphenol/thiophenol is one of the most important polymer precursors for synthesis of poly(aryl ethers) or poly-(aryl sulfides) in displacement polymerizations. Commonly used bisphenols are 4,4 -isopropylidene diphenol or bisphenol-A (BPA) due to their low price and easy availability. Other commercial bisphenols have also been reported [7,24,25]. Recently, synthesis of poly(aryl ethers) by the reaction of new bisphenol monomers with activated aromatic dihalides has been reported. The structures of the polymer precursors are described in Table 2. Poly(aryl ether phenylquinoxalines) have been synthesized by Connell et al. [26], by the reaction of bisphenols containing a preformed quinoxaline ring with... 

Other salts, especially fluoride salts, (e.g., KF) can be used to perform nucleophilic substitution. As is well known, halides, and particularly the fluoride anions, are rather powerful Lewis bases and can exert a catalytic effect on aromatic nucleophilic substitutions in dipolar aprotic solvents. Phenols can be alkylated in the presence of KF (or CsF) absorbed on Celite64,65 or Et4NF.66 Taking advantage of this reaction, halophenols and dihalides with bisphenols have been successfully polymerized in sulfolane at 220-280°C by using KF as the base. 

More attention has been devoted to aromatic and heteroaromatic substrates since first reported in 1983 [40]. The results are shown in Table 2 [25, 41-51]. All these reactions were run with nickel complexes associated with a phosphane or bpy ligand. Depending on the experimental conditions, the polymers were either precipitated during the electrolysis or deposited as films at the surface of the electrode. The method is also convenient to prepare copolymers from a mixture of two aryl dihalides. A mechanistic investigation on the nickel-bpy catalyzed polymerisation has been reported very recently [52]. 

The transition metal-catalysed coupling reaction of aryl halides with alkynes (alkynylation of aryl halides) is frequently also considered as a Heck reaction [68, 108-111], Polymers containing arylacetylene and diarylacetylene units in the backbone have been obtained by the self-coupling of ethynylaryl halides [scheme (3)] and the cross-coupling of aromatic dihalides with acetylene [scheme (6)] or diethynylbenzenes [scheme (7)] [112-121]. The majority of... 

Crown ethers948 and their sulfur equivalents949,950 may be synthesized by reaction of diols (or dithiols) with a, co-dihalides in the presence of a base. Similar reactions have been used to prepare heterocyclic bissulfides951. Thianthrenes have been synthesized by dimerization of or/Zzo-chlorothiophenols in HMPA in the presence of triethylamine952. The same targets may also be prepared by reaction of ortho-dihalo aromatic compounds with aryl dithiols with photostimulation275,953. 

The reaction of aryltellurium trichlorides 116 with activated aromatics 117 gives the corresponding diaryltellurium dihalides 118, which by reduction give the diaryl tellurides 119.5 11 12 55... 

In the case of phenyl isocyanide, both the addition of f-BuLi and an ortho lithiation took place in the presence of TMEDA to provide the intermediate 53 and finally compounds 54 and 55 (Scheme 15)75. The corresponding 3-metalloindolines (metal = S, P, Si, Ge, Sn) were obtained by reaction of the dilithium intermediate 53 with metal dihalides. The obtained benzazaphospholes and benzazarsoles 54 (M = f-BuP, MeAs) can be converted into the aromatic III-1,3-benzazaphospholes and benzazarsoles 55 by flash vacuum pyrolysis76. 

A less commonly employed method of preparation is the Kirsanov reaction.3 Strictly speaking, this is the reaction of phosphorus pentachloride with benzene-sulfonamide, which can be reacted further to form benzenesulfonyliminophos-phoranes. However, the name is now used generically to cover the reactions of triphenylphosphorus dihalides and amines in the presence of a base (Scheme 5). Attack of the amine on phosphorus gives the intermediate aminophosphonium salt and HBr, elimination of another equivalent of HBr generates the IMP. If the amine is aromatic, then 2 eq. of a mild base (e.g. triethylamine) are sufficient to perform the reaction in one pot.4 However, in the case of alkylamines, it is generally necessary to isolate the phosphonium salt and treat it with sodamide to effect the deprotonation and generate the IMP.5... 

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