Conformational Preferences for 3-piperideines: an Ab Initio and Molecular Mechanics Study

Conformational preferences in alkyl- as well as Ph-substituted 3-piperideines (1,2,3,6-tetrahydropyridines) have been characterized by ab initio and molecular mechanics calculations. A set of rules and subrules for estimation of the conformational equilibrium (in terms of preferred substituent orientation) in these systems. with differently positioned ring substituent (-s), is presented. Examples of the revision of some previous stereochemical assignments demonstrate the reliability of these rules.