Yu. N. Portnov

Synthesis and autooxidation of 2-amino-1,3-dialkylindoles

Autooxidation occurs during the liberation of the bases from the salts of 1,3-dialkyl-2-aminoindoles, and stable 3-hydroperoxides are formed. The same compounds can also be obtained without prior isolation of the salts via heterocyclization of 1-acyl-2-arylhydrazines. If one of the nitrogen atoms is not alkylated, the corresponding 3-hydroxy compounds are obtained.

Preparation of N-arylamino-2-pyrrolidones from arylhydrazides of γ-chlorobutyric acid

Intramolecular alkylation of the arylhydrazides of γ-chlorobutyric acid in the presence of sodium ethoxide leads to the formation of N-arylamino-2-pyrrolidones. The direction of the reaction is not altered by the absence of a substituent on the aniline nitrogen atom. In the case of a p-nitrophenyl-hydrazide, O-alkylation is observed.

Heterocyclization of acid arylhydrazides to 2-aminoindole derivatives (the Kost reaction) (review)

The results of research on the synthesis of 2-aminoindole derivatives by means of the rearrangement of acid arylhydrazides (the Kost reaction) are correlated.

Reaction of phenylhydrazides of N-acyl-?-phenyl-?-alanine with phosphorus oxychloride

The reaction of N′-methyl-N′-phenylhydrazides of N-acyl-β-phenyl-β-alanine with phosphorus oxychloride is accompanied by cleavage of the C-N bond in the intermediately formed 2-aminoindole derivative and, after splitting out of an amide fragment, leads to 1-methyl-3-benzylidene-2-iminoindoline and nitriles. Pyrimido [4,5-b] indoles — products of cyclization of the corresponding intermediate 2-aminoindole derivatives — were isolated from the reaction mixtures in low yields. The structure of 1-methyl-3-benzylidene-2-iminoindoline was proved by alternative synthesis.

Synthesis of 2-amino-3-(?-aminoalkyl)indoles

Abstract2-Amino-3-(ω-phthalimidoalkyl)indoles have been obtained by the rearrangement of ω-phthalimido acid β-phenylhydrazides under the action of POCl3. The possibility has been studied of eliminating the phthalyl protective group from these compounds and a convenient method has been developed for obtaining 2-amino-3-(ω-aminoalkyl)indole dihydrochlorides. The behavior of the 2-amino-3-(ω-phthalimidoalkyl) indoles in alkylation reactions has been investigated.

Electrophilic substitution in the 1-phenyl-2-acylpyrazolidine series

Bromination, nitration, and sulfonation reactions in the acylphenylpyrazolidine series were investigated. 1-(p-Bromophenyl)-2-acylpyrazolidines are formed in good yields in the bromination of these compounds over a wide range of temperatures in various solvents. Removal of the acyl group takes place simultaneously with sulfonation in the para position of the phenyl ring in the sulfonation of phenylacylpyrazolidines with concentrated sulfuric acid at room temperature; the p-sulfophenylpyrazolidines formed in this case exist in the form of betain structures. The nitration of acylphenylpyrazolidines with concentrated nitric acid (sp. gr. 1.52) leads to 1-(2,4-dinitrophenyl)-2-acylpyrazolidines. However, the nitration of these compounds with dilute nitric acid (sp. gr. 1.35) is accompanied by pronounced resinification; both 2,4-dinitrophenyl and p-nitrophenyl-2-acylpyrazolidines, as well as dimers of the latter, were detected among the reaction products.

Heterocyclization of N-propionylaminoindoline

Treatment of N-propionylaminoindine with a solution of phosgene in benzene gives the 1-[(indolin-1-yl)imino]propyl ester of 7-(1-cyanoethyl)indoline-1-carboxylic acid. The structure of the compound was proved using1H and13C NMR spectroscopy.

Reaction of a 2-aminoindole with difunctional compounds

The reaction of a 2-aminoindole with arylidenemalonic and arylidenecyanoacetic esters was studied. The effect of substituents in the benzene ring of the arylidenemalonic ester on the reaction pathway is demonstrated.

meta-Substituted arylhydrazides in the Kost reaction

Kost cyclization of meta-substituted arylhydrazides results primarily in the formation of mixtures of 4- and 6-substituted 2-aminoindoles.

Regioselectivity of the rearrangement of propionic acid N,N-diarylhydrazides under the conditions of the kost reaction

The transformation of propionic acid N,N-diarylhydrazides with electron-donor and electron-acceptor substituents in the aromatic rings under the conditions of the Kost reaction was studied. The ratios of the resulting isomeric N-aryl-2-aminoindoles were determined.