Aryl amide anions

Aryl Alkoxide and Aryl Amide Anions as the Nucleophiles... 

Aryl amide anions are bidentate nucleophiles allowing C—C bond formation and the synthesis ofaminobiaryls. PhNH- gives low yields of substitution with Arl under irradiation, whereas 2-naphthylamide ions react by a photoinduced SRN1 process... 

Alkyltriphenylphosphonium halides are only weakly acidic, and a strong base must be used for deprotonation. Possibilities include organolithium reagents, the anion of dimethyl sulfoxide, and amide ion or substituted amide anions, such as LDA or NaHMDS. The ylides are not normally isolated, so the reaction is carried out either with the carbonyl compound present or with it added immediately after ylide formation. Ylides with nonpolar substituents, e.g., R = H, alkyl, aryl, are quite reactive toward both ketones and aldehydes. Ylides having an a-EWG substituent, such as alkoxycarbonyl or acyl, are less reactive and are called stabilized ylides. 

S-Ethenylsulfimines 287 react with amides to yield 2-substituted-oxazolines 28 9 304 reaction proceeds via initial Michael addition of an amide anion to 287 to give 288 that collapses to the oxazoline. The reaction is typically carried out at room temperature or 50 °C in THF, 1,2-dimethoxyethane (DME), or even MeCN using NaH as the base. Aryl, heteroaryl, and aliphatic amides can be used and the yields of 289 are modest to excellent (Scheme 8.82). 

Reaction of the dilithio anion of 1-vinylbenzotriazole 90 with 2equiv of an aryl isocyanate led to a fused 1,4-diazepine ring formation via an intramolecular Michael addition of the intermediate aryl amide to the vinyl moiety, a type c ring closure that proceeded in good overall yield (Scheme 44) <2003JOC5713>. 

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. 

On the basis of the labeling experiment, an alternative mechanism was proposed for the substitution reaction of aryl halides with strong base-the elimination-addition mechanism. In the first step, the elimination stage, amide anion removes a proton from the carbon on the ring adjacent to the one with the halogen. The product is an unstable intermediate known as henzyne. 

In the second step, amide anion now acts as a nucleophile, adding to one of the carbons of the triple bond. This addition step gives an aryl anion. 

Intramolecular anionic dearomatization reactions have been developed starting from substituted naphthalenes and benzenes. Carbanions generated from deprotonation of A-benzyl aryl amides... 

Only few examples are present in the literature on aryl-N bond formation through the SrjjI mechanism. 2-Bromomesitylene has been found to undergo bromine substitution by amide anion affording 2-aminomesitylene in 70% yield, with only a small amount of dehalogenated derivative (see Scheme 4.33). The success of the reaction in this case was probably due to the precluded formation of benzyne intermediates from this reagent [179],... 

Figure 8.12 illustrates how a product study may not show what a mechanism is, but it can show what it is not. Reaction of the aryl halide with amide anion in liquid ammonia gives two products, in almost exactly equal amounts. This means that the replacement of chloride by an amino group cannot be a direct displacement, as this could give rise to only one of the products observed. In the second example, the stereochemistry of the product shows that it cannot have been produced in a simple one-step process—as this would give rise to a ci5-product. 

Antistatic polystyrenes have been developed in terms of additives or coatings to minimise primarily dust collecting problems in storage (see Antistatic agents). Large Hsts of commercial antistatic additives have been pubhshed (41). For styrene-based polymers, alkyl and/or aryl amines, amides, quaternary ammonium compounds, anionics, etc, are all used. 

A useful method to synthesize ten and fourteen-membered ring imides 346 involved an initial condensation of macrocyclic -ketoestes 343 with alkyl or aryl isocyanates and carbodiimides, respectively, in the presence of a base [68]. After a nucleophilic attack of the enolate on the isocyanate C, the resultant amide N anion 344 induced a ring closure by addition to the keto group. Then, the intermediately formed four-membered ring 345 underwent a fragmentation... 

Ammonium salts of alkenyl succinic half-amides have teen described for use as corrosion inhibitors in oil and gas production technology to combat corrosion by media containing CO2, H2S, and elemental sulfur [1366]. The inhibitor composition may contain a dispersing agent, such as a low molecular weight or polymeric anionic surfactant like an alkylsulfonic acid or an alkyl-aryl sulfonic acid. 

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