The Effect of Substituents on the Conformational Mobility of the Heterocycle in 1,4-Dihydropyrimidine and its Derivatives
Russian Chemical Bulletin
The equilibrium geometry of 1,4-dihydropyrimidine, 4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidine, and their alkyl (Me, Et, Pri, But) and phenyl derivatives has been calculated by molecular mechanics method. The equilibrium conformation of unsubstituted molecules is planar, but it is easily transformed to the boat conformation with a small change in the conformational energy. The effect of substituents on the geometry and conformational mobility of the dihydropyrimidine ring has been studied.