Conformational preferences for 3-piperideines: An ab initio and molecular mechanics study

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