Self-disproportionation of enantiomers of heterocyclic compounds having a tertiary trifluoromethyl alcohol center on chromatography with a non-chiral system

Self-disproportionation of enantiomers of heterocycles having a tertiary trifluoromethyl alcohol center on an achiral silica-gel stationary phase is discussed. During the chromatographic separation of an enantiomerically enriched mixture of 1-(3,4-dimethoxyphenethyl)-3-hydroxy-3-(trifluoromethyl)-6,7-dihydro-1H-indole-2,4(3H,5H)-dione (1) by eluting with ether on a non-chiral regular silica-gel significant enantiomeric enrichment was observed. Separation of non-racemic samples of 1 with enantiomeric excess values of 10-54% was carefully investigated: enantiomerically pure 1 with 99.9% ee was obtained by the use of 1 with at least 40% ee. A remarkable enantiomeric enrichment in the faster eluting fractions was also observed for compound 1 with only 30% ee to transform into 80% ee. Other enantiomeric mixtures of heterocyclic molecules containing a trifluoromethyl alcohol moiety at their quaternary carbon center were also examined from an SDE view point.     

The analysis of some heterocyclic compounds

The mass spectra of some relatively simple sulphur compounds have been obtained. Comments upon the McLafferty rearrangement are reported.     

The pyrylation of aromatic and heterocyclic compounds

Pyrylium salts having no substituents in position 4 react with aromatic and heteroaromatic compounds forming 4-aryl- and 4-heterylpyrylium derivatives. The reaction takes place through the stage of the formation of a pyran which, with an excess of the initial pyrylium salt, splits out a hydride ion, aromatizing into a trisubstituted pyrylium cation.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 6, pp. 733–738, June, 1970.     

Stereochemistry of heterocyclic compounds

Summary The stereochemistry of the reaction of 1-alkyl-4-piperidones with phenyllithium depends not only on steric factors, but also on the character of the nitrogen-attached alkyl group. The effect of alkyl groups is associated with fixation of the direction of the dipole of the nitrogen atom, as a result of which the predominant direction of reaction becomes that for which the free electron pair of the nitrogen and the C-O bond of the enolate ion then arising occupy antiparallel directions.     

Stereochemistry of heterocyclic compounds

Summary On the basis of a number of chemical reactions, views are expressed on the possible steric structure of 1, 2, 5-trimethyl-4-ethyl-4-piperidinol isomers (I,, ), the corresponding acetylenic alcohols (II, ,), and certain piperidine derivatives obtained from them.     

Diazo compounds of the heterocyclic series

2-(N-Nitrosamino)benzimidazoles in aqueous solutions or in organic solvents are spontaneously converted to 1,3-di(2-benzimidazolyl)triazenes. Other methods for the synthesis of triazenes of the benzimidazole series and their properties are examined.     

Stereochemistry of heterocyclic compounds

Summary The O-acetates of the four isomers of decahydro-4-quinolinol were synthesized, and on the basis of the inability of these to undergo rearrangement into the corresponding N-acetates it was suggested that the method of O N acyl migration is inapplicable in the series of decahydro-4-quinolinol derivatives.     

Polarography of heterocyclic compounds

The literature data on the principles of the electrochemical reduction of heteroethylene and heteroparaffin compounds (pyrazoline, diazepine, diaziridine, pyran, pyridazone, aziridine, oxaziridine, and other derivatives), cyclic anhydrides, imides, and hydrazides of acids on a dropping mercury electrode are correlated. In addition, the effect of substituents attached to the heterocyclic ring on the polarographic behavior of heterocycles is analyzed.     

Diazo compounds of the heterocyclic series

Stable primary N-nitrosamines of the benzimidazole series were obtained by the action of sodium amide and isoamyl nitrite on 1-substituted 2-aminobenzimidazoles and subsequent acidification of the resulting benzimidazole-2-diazotates. The effect of the acidity of the solution on the activity of the benzimidazole-2-diazonium salts formed from the nitrosamines was traced.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 689–692, May. 1974.     

Use of o-hydroxyaminobenzoic acid for the preparation of heterocyclic compounds

Anthranilic acid and its derivatives are widely used for the synthesis of nitrogen-containing benzoheterocycles, while its analog o-hydroxyaminobenzoic acid has been used only to prepare unsubstituted 2,1-benzoisoxazolone ¦1¦.     

Iodonium derivatives of heterocyclic compounds

5-Phenyliodonio-2,4-dihydroxypyrimidine tosylate (I) was obtained from the reaction of uracil with phenyl iodosoacetate in the presence of p-toluenesulfonic acid. Treatment of I with alkali gave 5-phenyliodonio-2,4-dihydroxypyrimidine (II). 5-Phenyliodonio-2,4-dihydroxypyrimidine chloride, bromide, iodide, and fluoborate were obtained. The IR and UV spectra were recorded, and the ionization constants were calculated. The phenyliodonium residue increases the acidity of uracil at N₍₁₎ by 3.5 orders of magnitude and at N₍₃₎ by two orders of magnitude.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 553–555, April, 1973.