title: Stereoelectronic effects in cyclic sulfoxides, sulfones, and sulfilimines: application of the Perlin effect to conformational analysis.
abstract: The 1JC--H coupling constants in conformationally constrained sulfoxides, bissulfoxides, sulfoxide-sulfones, and sulfilimines derived from 2-benzylidene-1,3-dithiane and 2-(2,2-dimethylpropylidene)-1,3-dithiolane were measured by means of HMQC and HSQC NMR experiments and the Perlin effects were calculated. The type and the relative configuration of S==X groups (X= O, NTos) in these compounds have a strong influence on the magnitude of coupling constants for axial and equatorial C--H bonds, respectively. Axial S==O bonds give rise to a stereoelectronic effect on antiperiplanar axial C--H bonds. The resultant weakening of the respective C--H bonds leads to a smaller coupling constant than for a respective equatorial C--H bond. Equatorial S==O groups have an influence on beta-C--H bonds through a homoanomeric effect. Here, the axial C--H bond is weakened and a smaller coupling constant is measured. Sulfilimine groups show similar effects to sulfoxide groups.
authors.affiliation: Institut für Organische Chemie der Universität Karlsruhe TH, Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Wedel
authors.forename: Monika
authors.initials: M
authors.lastname: Müller
authors.forename: Joachim
authors.initials: J
authors.lastname: Podlech
authors.forename: Helmut
authors.initials: H
authors.lastname: Goesmann
authors.forename: Claus
authors.initials: C
authors.lastname: Feldmann