Coupling, of benzenediazonium chloride

Coupling, of benzenediazonium chloride with acetoacetic acid, 32, 84 of diazotized 3,5-dichloro-2-amino-benzoic acid to give 4,4, 6,6 -tetra-chlorodiphenic acid, 31, 96 of diphenyldichloromethane to tetra-phenylethylene, 31, 104 Crotonaldehyde, diethyl acetal, 32, 5 Cyanoacetamide, 32, 34 Cyanoacetic acid, 31, 25 -Cyanobenzaldehyde, 30, 100 3-Cyano-5,6-dimethyl-2(l)-pyridone,... 

Long-range C-N couplings have been reported by Lycka et al for the product of the coupling of benzenediazonium chloride with 1,3-dihydroxy-naphthalene and benzenediazonium chloride with 1,5-dihydroxynaphthalene. 

Coupling, of benzenediazonium chloride with acetoacetic acid, 32, 84 of diazotized p-aminoacetophenone with quinone, 34, 1... 

Write the products of diazo coupling of benzenediazonium chloride with each of the following molecules, (a) Methoxybenzene (b) l-chloro-3-methoxybenzene (c) l-(dimethylamino)-4-(Ll-dimethylethyl)benzene. (Hint Diazo couplings are quite sensitive to steric effects.)... 

The coupling of benzenediazonium chloride with m-phenylenediamine in acid medium gives Basic Orange 2 (Chrysoidine), a dye of limited use on textiles but of importance for coloring paper, leather, and woodstains. 

Diphenylbutadiene has been obtained from phenylacetic acid and cinnamaldehyde with lead oxide, by the dehydrogenation of l,4-diphenyl-2-butene with butyllithium, and by the coupling reaction of benzenediazonium chloride and cinnamyl-ideneacetic acid." The present method gives better yields than those previously reported, is adaptable to the preparation of a variety of substituted bistyryls, and is relatively easy to carry out. 

The behavior of bis(heteroaryl)methanes in which the heterocycle was an electron-withdrawing group was similar to that typically exhibited by active methylene compounds. Bis(2-benzothiazolyl)methane and bis(2-(5-ethoxycarbonyl-4-methyl)thiazolyl)methane readily underwent azo-coupling with benzenediazonium chloride, nitrosation with nitrous acid and condensation with aromatic aldehydes under mildly basis conditions, such as in the Knoevenagel procedure. [94G301]... 

Strychnidine has not been halogenated or nitrated, but has been coupled with benzenediazonium chloride to give a 2-phenylazo derivative (44), reduced to 2-aminostrychnidine. Reduction of 2-nitrostrychnine gives 2-aminostrychnine (42). 

Another synthesis of u-triazolo[4,5-d]p5nrimidines described first by Benson et and by Hartzel and Benson also involves closing the triazole ring. It proceeds from a derivative of 4-aminopyrimidine (166), and making use of the aromatic character of the 5-position in the pyrimidine nucleus produces 4-amino-5-arylazo derivatives (167) by coupling with benzenediazonium chloride. These derivatives under-... 

If the coupling reaction of ethyl (4,6-diamino-3,5-dicyano-2-pyridyl)acetate with benzenediazonium chloride is performed in pyridine at 0°C, an oil results which, by refluxing in dimethylformamide, gives the cyclization product.64 In a one-pot reaction, 2-amino-3-benzoyl-5-cyano-4-phenylpyridine-6-acetonitrile, or the corresponding ethyl acetate, is coupled with benzenediazonium chloride in aqueous ethanolic sodium hydroxide, the mixture then left at room temperature to give 2-amino-3-benzoyl-5-imino-4,6-diphenyl-5,6-dihydropyrido[2,3-fi(]-pyridazine-8-carbonitrile (22a) or the ethyl 8-carboxylate 22b.65... 

The 2-oxocyclopentane-l-carboxylic ester 36 is coupled with benzenediazonium chloride in a basic medium with simultaneous acid cleavage of the product 37. The resulting phenylhydrazone of the a-... 

Isomerizations in which an H-atom changes its position in a heterocyclic system are known as annular tautomerisms. This is a special case of prototropy (prototropic rearrangement) [57]. For isoindole, the position of the equilibrium depends to a large extent on the type of the substituent in the 1- and/or 3-position [58]. The 1-phenyl compound exists in the 2//-form and couples with benzenediazonium chloride in the 3-position. 

Lactoflavin 20 (riboflavin, vitamin B2) was established by Kuhn and Karrer (1935). It is synthesized by condensation of 3,4-dimethylaniline with D-ribose giving the imine 21, followed by reduction to 22 and coupling with benzenediazonium chloride producing the azo compound 23 reaction of 23 with barbituric acid, after loss of aniline and cyclocondensation of the intermediate 24, yields lactoflavin 20. 

C,H5N,NHC,Hs+HC1 = C,H 5N C1+H,NC,H5- C H5N NC H NH +HC1 gen atom of the aniline molecule, giving aminoazobenzene. Since this reaction is irreversible, whilst the former is freely reversible, the final result is the complete conversion of the diazoaminobenzene into the aminoazobenzene. (The intermediate formation of the benzenediazonium chloride can be demonstrated by adding dimethylaniline, with which the diazonium chloride couples preferentially, giving dimethylaminoazobenzene, C6HsN NC6HiN(CH3)i.)... 

Barbituric acid can be considered as a cyclized malonic acid diamide (malonyl-urea). It is therefore a cyclic diketone that may be classified, in the sense of the compounds discussed in Section 12.6, as a coupling component with a methylene group activated by two carbonyl groups in the a- and a -positions. The reaction with arenediazonium salts was studied by Nesynov and Besprozvannaya (1971). These authors obtained coupling products (in good yield) that they considered to be arylhydrazones. Coupling with 4-(phenylazo)benzenediazonium chloride was studied by Chandra and Thosh (1991). The lH NMR spectra of these compounds are consistent with the arylhydrazone structure 12.68. 

The same authors <2000J(P1)3584> studied the reactivity of 2 toward benzenediazonium (chloride or tetrafluoro-borate) salts. No diazo coupling took place under neutral or slightly acidic conditions. However, under basic conditions (NaOH in H20/MeOH), a mixture of 62 and 63 was obtained. This result clearly indicates that the diazo coupling takes place through the anion of 62 which arises from the base-catalyzed methanolysis of amide 2 in which the pyrrole ring is obviously not nucleophilic enough. 

Diazo coupling has considerable technical value, because the azo compounds that are produced are highly colored. Many are used as fabric dyes and for other coloring purposes. A typical example of diazo coupling is formation of 4-A, V-dimethylaminoazobenzenc from benzenediazonium chloride and MA-dimethylbenzenamine ... 

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