OBSERVATIONS ON THE KARPLUS CURVE IN RELATION TO THE CONFORMATION OF THE 1,3-DIOXOLANE RING

Abstract

The experimental evidence indicates that the Karplus curve, which relates the coupling constant between hydrogens on vicinal carbons and the dihedral angle defined by the hydrogens, is subject to displacement. An upward displacement of 2.2 c.p.s. is required to account for the coupling constants found for the neighboring hydrogens in both 1,3-dioxolane and its 2,2-dimethyl derivative. On this basis, the compounds exist in conformations wherein the cis neighboring hydrogens define dihedral angles of 35° and 41°, respectively.