The Stereochemistry of the Quaternization of 5-Methyl-5-nitro-1, 3-dialkylhexahydropyrimidines

The proportions of isomers existing in the quaternization products were estimated from the nuclear magnetic resonance (NMR) and thin-layer chromatography data. Based on those data, the stereoselectivity of the quaternization of some 5-methyl-5-nitro-1, 3-dialkylhexahydropyrimidines with alkyl iodide was discussed. NMR characteristics and particularly the chemical shifts of axial and equatorial N-methyl and N-ethyl groups were used to assign the configurations.