The inversion of correlation between γ-effect values and dihedral angle: nontraditional chairboat conformational equilibrium in seven- and eight-membered dithioacetals

Abstract

13C NMR γ-anti effect data versus dihedral angle RCXC (X=O, S; R=Me, Ph, t-Bu) in a series of six eight-membered cyclic acetals and dithioacetals are summarized. The inversion of Lambert's correlation, determined for carbocycles, has been derived. X-Ray data for chair and boat forms of eight-membered cyclic dithioacetals is presented and the equilibrium of these structures is discussed. © 1989.