CONFORMATIONAL-ANALYSIS OF 2-OXO-1,2,3,4-TETRAHYDROPYRIDINE AND ITS ALKYL-SUBSTITUTED AND PHENYL-SUBSTITUTED DERIVATIVES

The molecular geometries and inversion barriers of the rings in 2-oxo- 1,2,3,4-tetrahydropyridine and its alkyl-substituted (Me, Et, Pr-i, or Bu-t) and phenyl-substituted derivatives were calculated by the molec ular mechanics method. The introduction of substituents has no substan tial effect on the equilibrium conformation of the heterocycle (a dist orted sofa). For 4-alkyl- and 3-alkyl-substituted derivatives (except for 4-Me and 4-Et derivatives), an axial orientation of the alkyl grou p is more favorable. The phenyl substituents have equatorial and axial orientations at positions 4 and 3, respectively.