Trihalides reaction with aromatic

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. 

Bisarene chromium compounds have been shown to undergo reversible exchange with aromatic hydrocarbons in the presence of aluminum trihalides (207). The exchange reaction has been used to improve the preparation of the bisbenzene chromium cation via the more readily prepared bismesitylene chromium cation 157b). 

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... 

Reaction with Allylic Halides, Alcohols, and their Derivatives. Allylation of allyl and propargyl trimethylsilyl ethers as well as benzyl and propargylic alcohol derivatives proceeds in the presence of a catalytic amount of Lewis acids, such as ZnC, TMS(OTf), and B(C6F5)3. Direct substitutions of the hydroxyl group of allylic, ben-zylic, and propargylic alcohols are catalyzed by HN(S02F)2, a rhenium-oxo complex, and InCls (eq 27). A combination of chlorodimethylsilane and allyltrimethylsilane effectively promotes the deoxygenative allylation of aromatic ketones in the presence of a catalytic amount of an indium compound, such as indium trihalide or metallic indium (eq 28). Allylation of cyclic allylic acetates with allyltrimethylsilane can be catalyzed by molecular iodine. ... 

Photocycloadditions of naphthalene derivatives to alkcnes have been recently reviewed.60 Examples of such reactions are the photocycloaddition of naphthalene to 2,3-dihy-drofuran,61 of 4-methoxy-l-naphthonitrile to acrylonitrile62 and of 2-trimethylsiloxynaph-thalene to methyl acrylate.63 2-Naphthols undergo cycloaddition with ethene in the presence of aluminum trihalides only.64 Other bicyclic aromatic compounds, e.g. A-acylindoles65-67 and /V-methylphenanthrene-9,10-dicarboximide,68 have also been studied in detail. Irradiation of 5/f-dibenzo[u,i7]cyclohepten-5-one (21) and dimethyl 2-methylfumarate (22) in dioxane gives the cyclobutane adduct 23 in 73% yield.69... 

Aryltellurium trichlorides 5 (R = aryl, X = Cl) are usually yellow, very stable crystalline solids, with a slight odor of hydrochloric acid, which probably arises from the reaction of 5 with the air moisture. Contact of 5 with metallic spatulas, with moist solvents, or prolonged exposure to light must be avoided. These compounds, however, can be handled in the air with no risk of decomposition. Aryltellurium tribromides (5, R = aryl, X = Br) are yellow crystalline solids, and the triiodides (5, R = aryl, X = 1) are dark red solids. The aryltellurium tribromides and triiodides were less explored for synthetic purposes, in contrast to the aryltellurium trichlorides, which were frequently used in several synthetic transformations. The aliphatic tellurium trihalides are less stable than the aromatic ones and were much less studied and used for preparative purposes. 

Tellurium tetrachloride and tetrabromide react with equimolar quantities of aryl mercury chlorides to produce aryl tellurium trihalides in high yields. This reaction is useful when the trichlorotelluro group is required at a specific position in the aromatic molecule or when tellurium tetrachloride does not condense in an acceptable manner with the aromatic hydrocarbon. The solvent of choice is dioxane, because mercury dichloride precipitates as the dioxane adduct, facilitating the isolation and purification of the aryl tellurium trichlorides. 

The polynuclear cation [(CeHe)3Co3(CO)2] has been reported from the reaction of Hg[Co(CO)4]a or Coa(CO)0 with benzene in the presence of an aluminum trihalide (66, 114). The cation is believed to have the structure (XXXI) analogous to (7r-C5H5)3Ni3(CO)a (289). Neutral polynuclear complexes of the type (arene)Co4(CO)g (arene = benzene, toluene, anisole, />-xylene, mesitylene, tetrahydronaphthalene) have been prepared by the reaction of (RC=CH)Co2(CO)e (R = H or Ph) with norbornadiene in the appropriate aromatic solvent or in some cases by simply warming Co4(CO)i2 with the arene (247, 365). The compounds are believed to have the structure (XXXII) derived from that of Co4(CO)i2 (435) by replacement of three apical CO groups by the arene. A normal coordinate analysis has been carried out on several of... 

The nature of donor-acceptor complexes has been the subject of various NMR studies conducted as early as the 1960s. Early calorimetric studies showed that boron trihalides are capable of forming donor-acceptor complexes with a number of Lewis bases and the heats of adduct formation for some of these complexes were determined. Gaseous boron trifluoride, for example, was shown to form a ctxnplex with ethyl acetate in a highly exothermic reaction (-A// = 32.9 0.2 kcal mol ). IR and UV analysis of BF3 complexes of aromatic aldehydes indicated a o-complex with a lengthened CVO bond and a highly delocalized ir-system. More detailed structural information, however, was acquired only after closer inspection by low temperature H, B, C and F NMR studies. ... 

Friedel-Crafts acylation The reaction of an acyl halide, using stoichiometric amounts of a Lewis acid such as aluminium trihalide, with an aromatic compound to form the acylated derivative. This variation avoids the polysubstitution that commonly occurs in the Friedel-Crafts alkylation reaction. 

Due to their close relationship with carbonic acid halides, cyanuric halides can undergo Friedel-Crafts-type reactions which lead to the formation of C-C bonds between the triazine ring and an aromatic compound. By analogy, the conversion is catalysed by Friedel-Crafts catalysts such as aluminum trihalides, heavy-metal salts, and protonic acids. Generally, the hydrogen halide formed is evaporated or trapped by a base96,91,113-124... 

An alternative method to prepare aromatic halo- or dihalo-phosphines is the reaction of a phosphorus trihalide with an arylmetal compound. Like the alkyl compounds, the metal must be a less electropositive one to avoid the formation of a tertiary phosphine, unless the arylmetal compound is sterically hindered. Older examples of syntheses by this method are the preparation of dichloro(l-naphthyl)phosphine (equation 25) and some dichloro(4-substituted-phenyl)phosphines (equation 26)". More recently, hindered aryllithium compounds have been treated with PCI3 to give dichloro(mesityl)phosphine or chlorodime-sitylphosphine" (equation 27), dichloro (2,4,6-tri-r rr-butylphenyl)phosphine (15) and dichloro[2,6-bis(trifluormethyl)phenyl]phosphine (16)." Aryldifluorophosphines have... 

A 8chiff-base condensation reaction apparently results from treating the rhenium metalla-acetylacetone complex (7) with primary aromatic amines (Scheme 1). The tetracarbonylrhenium /3-diketone molecule (7) reacts with boron trihalides to give compounds (9). ... 

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