K. F. Turchin

NMR SPECTRA OF NATURAL COUMARIN DERIVATIVES I. COUMARINS

SummaryThe NMR spectra of a series of linear and angular furocoumarins have been studied. A series of rules of interest for structural analysis in this series of compounds has been drawn up.

NMR spectra of natural coumarin derivatives

ConclusionsThe NMR spectra of nine coumarin derivatives have been studied. The results obtained may be used for purposes of structural analysis.

CYANOETHYLATION OF 2-CYANOMETHYLBENZIMIDAZOLE

The class of benzimidazole compounds contains some well-known drugs of various groups including spasmolytics (dibazole), neuroleptics (pimozide and droperidol), and antihistamines (astemizole) [ 1 ]. Condensation of the pyridine cycle with benzimidazole, that is, the passage to pyridobenzimidazoles, extends the spectrum of biological activity [2, 3]. A convenient intermediate for the synthesis of substituted pyridobenzimidazoles is l-(2-cyanoethyl)benzimidazol-2-ylacetonitrile (I):

SYNTHESIS OF QUINOLINE-4-CARBOXYLIC ACID AND ITS DERIVATIVES

Abstract2-Methylquinoline-4-carboxylic acid was obtained by the reaction of isatin with acetone in the presence of an alkali. This acid was converted through a step involving (E)-2-styrylquinoline-4-carboxylic acid to quinoline-2,4-dicarboxylic acid, from which quinoline-4-carboxylic acid was obtained by refluxing in nitrobenzene. The structures of the synthesized compounds were confirmed by 1H NMR spectroscopy using two-dimensional (2DJ) spectra.

Synthesis and psychotropic activity of 3-oxo-1,2,3,5-tetrahydropyrido[1,2-a]-benzimidazole-4-carboxylic acid arylamides

As is known, the GABA-A receptors are capable of interacting with various compounds containing heterobicyclic and/or heterotricyclic fragments and possessing high affinity for the so-called benzodiazepine binding sites. The main classes of these compounds are derivatives of benzodiazepine, 13-carboline, imidazopyridine, pyrazoloquinoline, and imidazoquinoxaline, among which there are substances exhibiting anticonvulsive, sedative, and anxiolytic activity [l]. As was recently established, 3-oxo-l,2,3,5-tetrahydropyrido[1,2-a]benzimidazole-4-carboxylic acid amides (I) are also capable of interacting with GABA receptors at the benzodiazepine binding sites [1]. This fact suggests that the group of amides I may contain compounds possessing psychotropic properties. In order to verify this hypothesis, we have synthesized a new group of amides ( I a Ig) on the basis of a principal scheme of synthesis suggested (without experimental details) previously [1]. A key compound in this scheme is the ethyl ester of 3-oxo-l,2,3,5-tetrahydropyrido[l,2-a]benzimidazole-4-carboxylic acid (II) obtamined proceeding from an ester of [ l-(2-cyanoethyl)benzimidazol-2-yl]acetic acid (III) as describred in the patent [2].

Conversions of the antitumor drug spirobromine in solutions. II. Alkaline solutions

In the first part of our investigation it was established by the method of NMR spectroscopy that spirobromine (I) in aqueous and hydrochloric acid solutions is converted to compounds with different substituents at the terminal nitrogen atoms of the spiro system, which is unaffectecd in the process. In this work the same method was used to show that not only conversions of the substituents but also reversible degradation of the spiro system occur in alkaline solutions of I.

sym-triazine derivatives. 8. Structure and further reactions of products formed in the reaction of 2,4,6-triethoxycarbonyl-sym-triazine with arylhydrazines

It has been demonstrated, based on detailed spectral analysis and chemical reaction studies, that the products of the reactions of arylhydrazines or semicarbazide with 2,4,6-triethoxycarbonyl-sym-triazine are 1,2,4-triazine derivatives.

sym-Triazine derivatives

The structures, tautomerism, and acid-base properties of some sym-triazinyl-substituted CH acids were studied.

Establishment of the configuration of 2,3,4, 4a, 9, 9a-hexahydroindeno[2,1-b]-1,4-oxazines according to 1H and 13C NMR data

It was shown by a study of the 1H and 13C spectra of derivatives of 2,3,4,4a,9,9a-hexahydroindeno[2,1-b]-1,4-oxazines that the investigated compounds are mixtures of cis- and trans-isomers. On the basis of a comparison of the chemical shifts of 13C in indanoxazines and stereoisomers of decalin, as well as the values of the spin-spin interaction constants of indanoxazines and indanopiperidine (J4a9a), it was concluded that the cis-isomer predominates in the mixture of isomers.

The spatial structure of the isomeric dimethyl esters of 4-hydroxypiperidine-2, 6-dicarboxylic acid

Three isomeric dimethyl esters of 4-hydroxypiperidine-2, 6-dicarboxylic acid have been isolated. The spatial structures of all three isomeric esters and of the acids corresponding to them have been established on the basis of NMR spectra. It has been shown that while the isomers I and II exist in the form of only one conformation each, isomer III in neutral and acid media apparently consists of an equilibrium mixture of two (or more) conformers. The information obtained on the spatial structure of the isomeric esters shows that the cyclization of these compounds with benzylamine and p-nitrobenzaldehyde takes place with the inversion of the piperidine ring.