7- Azaindole acetylation

The same reaction has been described on /V-acetyl derivative of 7-azaindole. Although the reaction represents a method able to obtain a new class of compound, the low yields of the product (4%) prevent from a synthetic use of this reaction [103]. 

The reaction of A-methyl-A-acetyl-2-chloro-3-amino tion in THF-hexane (-78 °C) gave azaindole in 83% yield used to prepare the key intermediate for the synthesis of Eupolauramine339. Thus, o-metallation of 3-bromopyridine and treatment with MeNCO gave the anion 319, which reacts with PhCOCH2Br forming the product 320 (equation 191). 

Clayton and Kenyon prepared 5-methyl, 2,5-dimethyl-, and 2-phenyl-5-methyl-4-azaindole in 12,55, and 67 % yields, respectively, by treatment of the corresponding formyl, acetyl, and benzoyl derivatives of 3-amino-2,6-dimethylpyridine with sodium ethoxide at 310° for 15 minutes. The phenyl compound was prepared also by Protiva et al in 1 % yield. 

Azaindoles are more stable to air oxidation than indoles, are stable to mild reagents like silver oxide and selenium dioxide, but are readily attacked by permanganate. In the structure proof of 7-aza-indole, Kruber oxidized the 1-benzenesulfonyl derivative with potassium permanganate in acetone solution to obtain 2-(benzene-sulfonyl)aminonicotinic acid. The 1-acetyl and 1-benzoyl derivatives gave inconsistent results, which Kruber attributed to their ease of hydrolysis. l-Benzoyl-2,5-dimethyl-4-azaindole and its 3-substituted derivatives give 3-benzamido-6-methylpicolinic acid with permanganate oxidation. ... 

Carbonation of the sodium salt of 7-azaindole (105, R = H) gives 7-azaindole-3-carboxylic acid (106, R = OH) in low yield. Robison and Robison also prepared it from 7-azaindole-3-carboxaldehyde (105, R = CHO) either by direct oxidation (28 % yield) or through the oxime, which was dehydrated with acetic anhydride to l-acetyl-3-cyano-7-azaindole. This compound was hydrolyzed in water to give 3-cyano-7-azaindole (105, R = CN) in refluxing hydrochloric acid it... 

Dimethyl-4-azaindole was found to couple with benzene-diazonium chloride to give the 3-phenylazo compound in 70% yield. It was reduced to the unstable 3-amine which was isolated as l-acetyl-3-acetamido-2,5-dimethyl-4-azaindole. The same compound was obtained by reduction of the nitration product of the parent. A small amount of 3-phenylazo-7-azaindole was obtained under similar conditions. ... 

Azaindoles are readily acylated on the pyrrole nitrogen by warming on a water bath with acid anhydrides or with acid chlorides in the presence of carbonate or pyridine. Good yields were obtained by this procedure for the following compounds l-acetyl-7-azaindole, 1-benzoyl- and l-benzenesulfonyl-7-azaindole, l-benzoyl-2-methyl-7-azaindole, 1-ethoxycarbonyl- and l-chloroacetyl-7-azaindole, l-acetyl-3-cyano-7-azaindole, 1-benzoyl-4-azindole, and 1-acetyl- and l-benzoyl-2,5-dimethyl-4-azaindole. The only reported failure was with 5-methyl-2-phenyl-4-azaindole, which failed to react with acetic anhydride or benzoyl chloride. 2-Methyl-7-azaindole-3-acetic acid was acylated by treatment of its ierGbutyl ester with sodium hydride in dimethylformamide, followed by p-chlorobenzoyl chloride. ... 

Nucleosides and their Derivatives and Related Compounds.—2 -0-Methyladeno> sine, adenosine 5 -phosphate (an orthorhombic form) and its barium salt, 3-deaza-adenosine, 2, 6-anhydro-l-j8-D-arabinofuranosylcytosine, 5,6-dihydroisocytidine, 5,6-dihydro-2,4-dithiouridine, 2,2 -anhydro-l-a-D-xylo-furanosyluracil, guanosine 5 -phosphate [the copper(n) and cadmium salts ], xanthosine, 6-methylthio-9-jS-D-ribofuranosylpurine, 6-benzyl-amino-9-)8-D-ribofuranosylpurine, 4-amino-5-jS-D-ribofuranosyl-5-azaindole, 2 - (3,4 - di - O - acetyl - 2 - deoxy - - l - erythro - pentopyranosyl) - 5,6 - dimethylbenzo -triazole, and 4,5-bis(carboxymethyl)-3-(2,3-0-isopropylidene-j3-D-erythro-furanosyl)-1 -(4-nitrophenyl)pyrazole. ... 

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