Aroyl anhydrides

Mesylates are used for Ni-catalysed reactions. Arenediazodium salts 2 are very reactive pseudohalides undergoing facile oxidative addition to Pd(0). They are more easily available than aryl iodides or triflates. Also, acyl (aroyl) halides 4 and aroyl anhydrides 5 behave as pseudohalides after decarbonylation under certain conditions. Sulfonyl chlorides 6 react with evolution of SO2. Allylic halides are reactive, but their reactions via 7t-allyl complexes are treated in Chapter 4. Based on the reactions of those pseudohalides, several benzene derivatives such as aniline, phenol, benzoic acid and benzenesulfonic acid can be used for the reaction, in addition to phenyl halides. In Scheme 3.1, reactions of benzene as a parent ring compound are summarized. Needless to say, the reactions can be extended to various aromatic compounds including heteroaromatic compounds whenever their halides and pseudohalides are available. 

These reagents can be prepared by reaction of halopyridines with activated Zn in THF. Coupling with ArX or (ArCOjiO In the presence of Pd(P(C6H5)3j4 these zinc reagents couple with aryl halides or aroyl anhydrides. It is particularly useful for preparation of unsymmetrical bipyridincs. 

A further example is given below illustrating the use of a dibasic anhydride (succinic anhydride) the succinoylation reaction is a valuable one since it leads to aroyl carboxylic acids and ultimately to polynuclear hydrocarbons. This general scheme of synthesis of substituted hydrocarbons through the use of succinic anhydride is sometimes called the Haworth reaction. Thus a-tetralone (see below) may be reduced by the Clemmensen method to tetralin (tetrahydronaphthalene) and the latter converted into naphthalene either catal3d.ically or by means of sulphur or selenium (compare Section, VI,33). 

Substituted aroyl- and heteroaroyltrimethylsilanes (acylsilanes) are prepared by the coupling of an aroyl chloride with (Me3Si)2 without decarbonylation, and this chemistry is treated in Section 1.2[629], Under certain conditions, aroyl chlorides react with disilanes after decarbonylation. Thus the reaction of aroyl chlorides with disilane via decarbonylation is a good preparative method for aromatic silicon compounds. As an interesting application, trimel-litic anhydride chloride (764) reacts with dichlorotetramethyidisilane to afford 4-chlorodimethylsilylphthalic anhydride (765), which is converted into 766 and used for polymerization[630]. When the reaction is carried out in a non-polar solvent, biphthalic anhydride (767) is formed[631]. Benzylchlorodimethylsilane (768) is obtained by the coupling of benzyl chloride with dichlorotetramethyl-disilane[632,633]. 

Tha.lliuin(I) Compounds. Carboxyhc anhydrides can be prepared by the reaction of acyl or aroyl haUdes in ether with thaHium(I) carboxjiates (26) ... 

R = OCHg, R = N(CHg)2] on treatment with polyphosphoric acid give the corresponding 2-aroyl-l-oxo-l,2,3,4-tetrahydro-j8-carboline (177). In the latter instance the use of acetic anhydride... 

Aroylation of 3-arylhydrazonoisatin with aroyl chlorides gave 1043, which cyclized with ammonium acetate to give [1,2,4]triazino[5,6-A>]indole 1044 (92MI1). Derivatives of 1045 were prepared (92MI1). Cyclocondensation of 5-ethyl-3-hydrazino-5/f[l,2,4]triazino[5,6-b]indole 165 with succinic anhydride in acetic acid gave pyridazinedione derivative 1046 (90MI7) (Scheme 197). 

Use of 2,4,6-trichlorobenzoyl chloride, Et3N, and DMAP, known as the Yamaguchi method,128 is frequently used to effect macrolactonization. The reaction is believed to involve formation of the mixed anhydride with the aroyl chloride, which then forms an acyl pyridinium ion on reaction with DMAP.129... 

Reduction of Methylene Violet with zinc in acetic acid gives the air-sensitive leuco 20 which is further reacted with acetic anhydride in mild conditions to yield the acetylated leuco 21. The latter being air stable can be isolated and, the ring N-H being less reactive is not affected by acetylation at room temperature. The leuco 21 is again aroylated to produce the leuco 22. Selective hydrolysis provides the desired leuco dye 12 which regenerates the true Methylene Violet (6) on oxidation.83... 

Electroluminescent phenantroline dyes containing triphenylamine and 1,3,4-oxadiazole fragments were prepared using tetrazole-oxadiazole interconversion performed in the presence of aroyl chlorides <2004TL6361>. Also, iV-tributylstannyltetrazoles treated with acetic anhydride gave oxadiazole derivatives <2002RCB357>. 

Solid Catalysts. Nafion-H is an active catalyst for acylation with aroyl halides and anhydrides.60,61 The reaction is carried out at the boiling point of the aromatic hydrocarbons. Yields with benzoyl chloride using 10-30% Nafion-H for benzene, toluene, and p-xylene are 14%, 85% and 82%, respectively. Attempted acylation with acetyl chloride, however, led to HC1 evolution and ketene formation. Nation resin-silica nanocomposite materials containing a dispersed form of the resin within silica exhibits significantly enhanced activity in Friedel-Crafts acylations.62,63... 

Fluorinated diaeyl peroxides have acquired an important role in organo-fluorine chemistry and have become the subject of intensive research.202-204 Bis(per)fluoroaIkanoyI or -aroyl peroxides are generally synthesized in excellent to moderate yields in the same manner as for nonfluorinated peroxides, that is by reaction of acid chlorides or anhydrides with sodium peroxide or hydrogen peroxide.205-206 Similarly, perfluoroalkanoyl chlorides and fluorides, many of which are accessible by industrial processes, react with hydrogen peroxide in the presence of hydroxide to give the diacyl peroxides l.206-207... 

Nafion-H has also been found to be an effective catalyst for heterogeneous acylation of aromatic hydrocarbons with aroyl chlorides and anhydrides.367... 

Aroylation of an aromatic system by reaction with phthalic anhydride under Friedel-Crafts conditions yields the o-aroylbenzoic acid. These readily available compounds have characteristic melting points which make them useful as derivatives in the characterisation of aromatic hydrocarbons and of aryl halides (Section 9.6.3, p. 1238). 

The aroylation of an aromatic system by reaction with phthalic anhydride under Friedel-Crafts conditions is described in Section 6.11.1, p. 1006. The cyclisation of the derived o-aroylbenzoic acid with polyphosphoric acid is a convenient route to substituted anthraquinones. The reaction is illustrated by the formation of 2-methylanthraquinone from o-(p-toluoyl)benzoic acid (Expt 6.132). 

Under certain conditions, aroyl chlorides are converted to arylsilanes by the reaction with disilanes. The oxidative addition of aroyl chloride and decarbonylation are followed by transmetallation and reductive elimination to give aryl silanes. Neat trimellitic anhydride acid chloride (377) reacts with dichlorotetramethyldisilane (376) at 145 °C to generate 378, which affords 4-chlorodimethylsilylphthalic anhydride (379) by reductive elimination. Finally it was converted to 380 and used for polyimide formation [185], Biphenyltetracarboxylic anhydride 381 is obtained at a higher... 

Sodium arenetellurolates condensed with aroyl chlorides6 to produce aroyl aryl tellurium derivatives (p. 501). Acetic and propanoic anhydrides reacted similarly7. Butyl aroyl or acyl tellurium compounds were obtained from reactions between lithium (sodium) butanetellurolates and aroyl chlorides6-8, acyl chlorides8, or acetic anhydride9. 

Carbodiimides are a unique class of reactive organic compounds having the heterocumu-lene structure R—N=C=N—R. They can be formally considered to be the diimides of carbon dioxide or the anhydrides of 1,3-substituted ureas, and they are closely related to the monoimides of carbon dioxide, the isocyanates. The substituent R can be alkyl, aryl, acyl, aroyl, imidoyl or sulfonyl, but nitrogen, silicon, phosphorous and metal substituted carbodiimides are also known. The unsubstituted carbodiimide HN=C=NH is isomeric with cyanamide, H2NCN. Mono substituted carbodiimides, generated in the thermolysis of 1-substituted tetrazoles, can be isolated at liquid nitrogen temperature but isomerize to the cyanamides at higher temperatures. ... 

Both acyl and aroyl halides and anhydrides react with aromatic compounds under Friedel-Crafts conditions to yield aromatic ketones (Scheme 6.23). 

Phenol, btomobenzene, i-butylbenzene, and acenaphthene give keto acids in good yields. The reaction is applicable to other aliphatic dibasic acid anhydrides like glutaric anhydride, adipic poly anhydride, and maleic anhydride, furnishing w-aroyl acids. An excellent discussion including experimental conditions and procedures has been given. Optimum conditions for the reaction of naphthalene, biphenyl, and chlorobenzene with phthalic anhydride have been determined. The Corresponding keto acids are obtained in 90-98% yields. In this type of condensation, nitrobenzene is stated to be far superior to other solvents with respect to solvent power and ability to slow side reactions. ... 

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