I. M. Skvortsov

Research on 1-azabicyclic compounds

Abstract1-(2-Furyl)-3-amino-4,4-dimethylpentane was used to obtain 3-tert-butyl-1,2-dihydropyrrolizine, the catalytic hydrogenation of which over Rh/Al2O3 at room temperature gives a mixture of cis- and trans-3,8-H-3-ter-butylpyrrolizidines with predominance of the cis isomer, whereas hydrogenation at 90–100 °C gives a mixture containing the trans isomer as the principal component. The three-dimensional structures of the isomers follow from data on the catalytic hydrogenation and isomerization and the IR, Raman, and PME spectra. A considerable percentage of the trans-fused form is characteristic for cis-3,8-H-3-tert-butylpyrrolizidine.

Investigation of 1-azabicyclic compounds

The conditions for carrying out the condensation of 1,2-dihydropyrrolizine, 2-methyl-1,2-dihydropyrrolizine, and 3-methyl-1,2-dihydropyrrolizine with ethylene oxide were investigated. The NMR spectra indicated that hydroxyethylation proceeds at the 5 and 7 positions of the 1,2-dihydropyrrolizine system.

Studies of 1-azabicyclics. 23. Nitration of 1,2-dihydropyrrolizine and its homologs

Nitration of 1,2-dihydropyrrolizine and its homologs with a mixture of nitric acid and acetic anhydride has been shown to give a mixture of 5-, 6-, and 7-nitro-1,2-dihydropyrrolizines. The distribution of isomers with respect to the position of alkyl substituents in the nonaromatic portion of the bicyclic is discussed.

Research on 1-AZA two-ring systems. 21. Basicities, stereochemistry, and 1H and 13C NMR spectra of pyrrolizidine and its homologs in aqueous and aqueous acetonitrile solutions. Prediction of the pKa value of trans-fused pyrrolizidine

The basicities of pyrrolizidine and its homologs in aqueous and aqueous acetonitrile solutions at 25 ° C were determined. It is shown that among 3-alkylpyrrolizidines, the isomers with cis configurations have higher pKa values than the isomers with trans configurations. On the basis of a comparative study of the 1H and 13C NMR spectra it was concluded that cis-3,8-H-cis-5,8-H-3,5-dimethylpyrrolizidine in aqueous solutions exists chiefly in the trans-fused form, whereas conformationally heterogeneous pyrrolizidines with primarily cis-fused rings experience a shift of the equilibrium to favor an increase in the cis-fused conformations when a nonpolar solvent is replaced by a polar solvent. The basicity of the trans-fused conformation of pyrrolizidine is predicted on the basis of the data obtained.

Research on 1-aza two-ring systems

Mixtures of isomeric 5-, 6-, and 7-carbethoxymethyl-1,2-dihydropyrrolizines were obtained by reaction of 1,2-dihydropyrrolizines with ethyl diazoacetate. The effect of the position of the alkyl groups in the two-membered ring on the ratio of isomers in the reaction products is demonstrated. A method for the isolation of 5-carbethoxymethyl-1,2-dihydropyrrolizines from the mixtures of isomers based on the difference in their reactivities in diazo coupling is described. The preferred conformations of the two-membered rings in the 5-carbethoxymethyl-1,2-dihydropyrrolizines are judged from the PMR spectral data.

Investigations in the field of 1-azabicyclanes

The stereochemistry of the catalytic hydrogenation of 5- and 7-(β-hydroxyethyl)-1,2-dihydropyrrolizines on 2.5% Rh/Al2O3 and Raney nickel under various conditions has been studied. On the basis of information on the configurational catalytic isomerization and the competing quaternization of the isomers, a consideration of the relative retention times, and an analysis of the geometries of the molecules of the 1- and 3-(β-hydroxyethyl)pyrrolizidines a configurational assignment of the stereoisomers has been made.

Investigation of 1-azabicycles

The composition of mixtures of epimeric 3-methylpyrrolizidines obtained by four methods was determined by gas-liquid chromatography (GLC). The data presented make it possible to select a method for the preparation of a mixture of isomers of 3-methylpyrrolizidine with predominance of trans- or cis-3,8-H-3-methylpyrrolizidine.

A study of the reaction mechanism of the catalytic intramolecular conversion of heterocycles

In order to study the reaction mechanism of the catalytic intramolecular conversion of heterocycles [1–3] and to broaden the field of their application, we have studied the dehydration over Al2O3 of 1-amino-3-(α-tetrahydrofuryl) propane (I), 1-methylamino-1-(α-tetrahydrofuryl) propane (II), and 2-(3-hydroxy-1-propyl)-1-methylpyrrolidine (III), leading in all three cases to pyrrolizidine (IV).

Studies of 1-azabicyclo compounds

Furan and tetrahydrofuran amines with the amino group at position 4 or 5 in the side chain are intramolecularly dehydrated to the corresponding 1-azabicyclo compounds when passed over Al2O3-ZrO2 catalyst at 325–330°.