Stereoelectronic Effects: Perlin Effects in Thiane-Derived Compounds

Article abstract of DOI:10.1002/ejoc.202000198

Stereoelectronic effects in thianes and thiane-derived sulfoxides, sulfones, sulfilimines, and sulfoximines were investigated by measuring ¹J_C,H coupling constants and by identification of normal and reversed Perlin effects, i.e., of differences in the coupling constants for equatorial and axial C–H bonds in the methylene groups of six-membered rings. The Perlin effects were correlated with results from natural bond orbital (NBO) analyses. NMR experiments were performed with conformationally restricted dimethyl- or tert-butyl-substituted derivatives, while the parent compounds were used for calculations. It turned out that the coupling constants are not only strongly influenced by stereoelectronic interactions with antiperiplanar C–H, C–C, C–O, and C–N bonds, but by the s character of the respective C–H bonds' carbon orbital as well.