L. G. Yudin

Closure of the pyridine ring in the combes quinoline synthesis (Review)

Closure of the pyridine ring in the Combes quinoline synthesis occurs by a type of intramolecular electrophilic substitution. With two free ortho positions the direction of ring formation depends both on the initial electrophilic attack, i.e., the nucleophilicity of the ortho carbon atom, and on the possibility of stabilizing the intermediate complex. The steric requirements of substituents both in the enaminoketone chain and in the position ortho to the point of attack exert a significant effect on the direction of ring closure. The steric factor is decisive when forming condensed angular quinoline structures.

Recyclization of 3-alkyl- and 1,3-dialkylisoquinolinium salts to naphthylamines

3-Methyl- and 3-benzylisoquinolinium salts undergo rearrangement to 2-alkylaminonaphthalenes under the influence of alcohol solutions of alkylamines. The rearrangement of 1,3-dimethyl- and l-methyl-3-benzylisoquinolinium salts leads to both 1- and 2-alkylaminonaphthalenes with predominance of the former.

Rearrangement of 2-hetarylalkylpyridinium salts

The rearrangement of 2-thienyl- and 2-furylalkylpyridinium salts to the corresponding anilines by the action of methylammonium sulfites has been studied. It has been shown that the rearrangement of these salts is accompanied in many cases by the formation of phenols and dealkylation products. The influence of the length of the alkyl chain between the heterocyclic rings on the ratio of the rearrangement products has been investigated.

Isomerization of the pyridine ring in salts of 1,2-dialkylisoquinoline

General Method of Obtaining Nitropyrroloquinolines ~III-VI). Compound (II) (0.38 mmole) was boiled in trifluoroacetic acid (5 ml) for 8 to i0 h. The cooled reaction mixture was poured into a diluted 10% solution of aqueous a~onia. The precipitated solid was filtered off, washed with water, and air-dried. The obtained mixture was separated on a binderfree thick layer of Al20a (activity Brockmann grade 2, benzene--ethyl acetate, 3:2). Yields and constants of substances are given in Table 3.

Synthesis of benzo(aminomethyl)indoles

The benzene ring in indoles has been aminomethylated in high yield by reaction with methylolphthalimide followed by hydrazinolysis of the phthalimidomethyl derivatives. In the hydrazinolysis of one of the phthalimidomethyl compounds, an intermediate product (the amino-methylindole phthalazine) was isolated and characterized.

Investigation of the recyclization of quaternary salts of papaverine and its structural analogs

The rearrangement of salts of the alkaloid papaverine and its structural analogs under the influence of nucleophilic agents was studied. It is shown that when an alcohol solution of an alkylamine is used as the reagent, replacement of the methoxy group in the 6 position of the isoquinoline ring by an alkylamino group takes place simultaneously with the rearrangement. Rearrangement with retention of the methoxy group can be carried out under the influence of an alkylammonium acetate.

Mass spectrometric study of ?-carbolines

A series of α-carbolines were subjected to mass-spectrometric analysis. It is shown that these compounds are extremely stable with respect to electron impact. From 40 to 60% of the total ion current goes into the production of molecular ions during dissociative ionization. The mass spectra of these compounds are simple: the maximum peak corresponds to the molecular peak in the spectrum. The formation of the [M-1]+ ion and the detachment of a methyl group in monomethylcarbolines ([M-15]) are determined by the position of the methyl group. The mass-spectral fragmentation confirms the proposed scheme for the formation of α-carbolines from arylhydrazones and δ6-keto nitriles. A method for the synthesis of α-carbolines on the basis of accessible arylsulfamidoindoles is proposed.

Synthesis and reactions of benzoformylindoles

A method was developed for the synthesis of 5- or 6-formylindoles by reaction of 5- or 6-aminomethylindoles with hexamethylenetetramine in acidic media. 1-Methyl-7-formylindole was obtained by recyclization of nicotyrine methiodide under the influence of alkaline agents. The corresponding vinylindoles were obtained by condensation of formylindoles with nitromethane, nitroethane, and malonic acid. The structures of the products were proved by alternative synthesis, the results of elementary analysis, and the UV, IR, PMR, and mass spectra.

MASS-SPECTRAL BEHAVIOR OF NITROHYDROXY- AND NITROMETHOXYMETHYLINDOLES

The principal pathways in the fragmentation of isomeric nitrohydroxy- and nitromethoxymethylindoles containing functional groups in the benzene ring were established by means of high-resolution mass spectrometry and deuterium labeling. The fragmentation of these compounds proceeds via different pathways as a function of the orientation of the functional substituants and the pyrrole nitrogen atom and differs from the fragmentation of other nitroarenes. The data obtained make it possible to reliably identify isomeric substances.

3-(indolylamino)vinyl ketones

The reaction of 5- and 6-aminoindoles with 1,3-diketones leads to 3-(indolylamino)vinyl ketones, which have an enamino ketone structure. A study of the mass-spectral fragmentation of the enamino ketones makes it possible to unambiguously determine the direction of the reaction and also to distinguish and identify isomeric pairs.