Aryl reactions

An aryl methane- or toluenesulfonate ester is stable to reduction with lithium aluminum hydride, to the acidic conditions used for nitration of an aromatic ring (HN03/H0Ac), and to the high temperatures (200-250°) of an Ullmann reaction. Aryl sulfonate esters, formed by reaction of a phenol with a sulfonyl chloride in pyridine or aqueous sodium hydroxide, are cleaved by warming in aqueous sodium hydroxide. ... 

The coupling of alkyl halides 1 upon treatment with a metal, e.g. elemental sodium, to yield symmetrical alkanes 2, is called the Wurtz reaction. Aryl alkanes can be prepared by the Wurtz-Fittig reaction, i.e. the coupling of aryl halides with alkyl halides. 

In addition to sodium, other metals have found application for the Wurtz coupling reaction, e.g. zinc, iron, copper, lithium, magnesium. The use of ultrasound can have positive effect on reactivity as well as rate and yield of this two-phase reaction aryl halides can then even undergo an aryl-aryl coupling reaction to yield biaryls. ... 

Aryl chlorides and bromides are prepared by reaction of an arenediazonium salt with the corresponding copper(I) halide, CuX, a process called the Sandmeyer reaction. Aryl iodides can be prepared by direct reaction with Nal without using a copper(T) salt. Yields generally fall between 60 and 80%. 

NMR spectroscopy, 93. See also Proton NMR integrations Hoechst continuous process, 548 Homo-coupling reactions, aryl halide, 486-487 Homopolymers, 7 Hot-cast prepolymer method, 211 Hot phosgenation, 222 Houvink-Sakurada equation, 286 HTMAB. See Hexadecyltrimethylammonium bromide (HTMAB)... 

In a related reaction, aryl halides couple with vinyl tin reagents to form styrene derivatives in the presence of a nickel catalyst, for example, ... 

Meerwein Arylation Reactions. Aryl diazonium ions can also be used to form certain types of carbon-carbon bonds. The copper-catalyzed reaction of diazonium ions with conjugated alkenes results in arylation of the alkene, known as the Meerwein arylation reaction.114 The reaction sequence is initiated by reduction of the diazonium ion by Cu(I). The aryl radical adds to the alkene to give a new (3-aryl radical. The final step is a ligand transfer that takes place in the copper coordination sphere. An alternative course is oxidation-deprotonation, which gives a styrene derivative. 

The subsequent steps involve, among several proposed reactions, arylation of the mercury cathode, and release of lead, but most importantly they indicate [ArPbH] as evidence for polymer formation by the proposed route ... 

In temperature-sensitive reactions, aryl aldehydes and ketones produce the trimethylcarbinols at ca. 0°C and the glycolic acids at ca. 56°C in competition with the base-catalysed Cannizzaro or condensation reactions [3, 5, 8]. 2- and 3-Formylpyridines produce the trichloromethylcarbinols (20-30%), whereas 4-formylpyridine undergoes the Cannizzaro reaction [9]. Formylferrocene is converted into the a-ferrocenylglycolic acid (35%) [10],... 

In the Mizoroki-Heck reaction aryl bromides and activated aryl chlorides could be employed with moderate turnovers. This holds true for both the complexes of monodentate such as 60 as well as the complexes of chelating ones... 

Hydroxamic acids undergo facile nucleophilic Ai-arylation with activated aryl halides such as 31 (equation 22). While hydroxamates are known to be ambident nucleophiles in alkylation reactions, arylation of hydroxylamines results exclusively in Ai-substituted hydroxamates of type 32 (equation 22)". ... 

Cuprous-catalyzed replacement reactions are called Sandmeyer reactions aryl chlorides, bromides, cyanides, and nitro compounds are prepared in this way formation of aryl iodides requires no catalyst, fluorides are obtained by heating diazonium fluoroborates (i.e., Schiemann reaction) benzenols are obtained by warming aqueous diazonium salt solutions. 

Keywords solid diazonium salt, potassium iodide, iodination, solid-solid reaction, aryl iodide... 

As noted for the Heck reaction, aryl, alkenyl, and alkynyl bromides, iodides, and triflates are best for the oxidative addition. However, aromatic, heteroaromatic, alkenyl, and even alkyl boronic acids and esters can be coupled effectively. The reaction appears almost oblivious to other functional groups present ... 

For example, via cross-coupling reactions arylated imidazoles, which are otherwise difficult to prepare from imidazoles, can be prepared in a direct reaction. 

Using conditions similar to those developed for fluorous Suzuki reactions, aryl sulfides were synthesized by reaction of fluorous sulfonates with thi-oles (Scheme 5) [32]. The reaction mixtures were in this case also purified by F-SPE. 

Benzanilides also undergo ortho arylation (Eqs. 9 and 10) [16]. For these reactions, aryl triflates as arylation reagents are more effective than aryl bromides. The reaction is also believed to proceed via coordination of amide anion to ArPd(II), because no reaction occurs with secondary amides. 

Diaryliodonium Salts Preparative Methods. Carbon-Carbon Bond-Forming Reactions. Arylation of Heteroatoms. 

Treatment of aryl tellurium halides with base (ethanolic potassium hydroxide6, aqueous sodium hydroxide7, triethylamine8, tris[< -propyl] phosphite8, triphenylphosphane8) leads to the formation of diaryl ditellurium compounds (p. 273). In the hydrolytically induced disproportionation reactions, aryl tellurinic acids are the other tellurium-containing products7,9. 

In a related reaction, aryl phosphates (prepared from the corresponding phenols) have been reduced to the parent hydrocarbon with Li or Na in Yields are increased if electron-donating groups are pres-... 

Ketones can be prepared from aryl aldehydes (ArCHO) by treatment with a rhodium complex (Ph3P)2Rh(CO)Ar, whereby the Ar group is transferred to the aldehyde, producing the ketone, Ar-CO-Ar. In a rhodium catalyzed reaction, aryl aldehydes (ArCHO) react with Me3SnAr to give the diaryl ketone Ar-CO-Ar. ... 

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