Stereoelectronic effects in thianes and thiane-derived sulfoxides, sulfones, sulfilimines, and sulfoximines were investigated by measuring 1 J 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) [a] Compounds 1-19 were used for NMR spectroscopic investigations, where 2,4-dimethyl-substituted compounds 17-19 were investigated for comparison. Only the sulfide 17, the equatorial sulfoxide 18, and the respective sulfone 19 were synthesized with this substitution pattern. The parent compounds 20-27 were used for calculations. Scheme 2. Synthesis of thiane 9. a) PhCHO, KOH, EtOH/H 2 O (78 %); b) O 3 , AcOH, 10°C, 5 h, then H 2 O 2 , reflux, 3 h; c) EtOH, cat. H 2 SO 4 , PhMe; Dean-Stark trap, 16 h (46 %); d) LiAlH 4 , Et 2 O, r.t., 16 h (93 %); e) MsCl, Et 3 N, CH 2 Cl 2 , r.t., 1 h (99 %); f) Na 2 S, EtOH/H 2 O, reflux, 2 h (78 %).Functionalization of thianes 1 and 9 was achieved with proven methods (Scheme 3). Oxidation with ozone yielded the equatorial sulfoxides 2 and 10, respectively, with good yields. [14] The axial sulfoxides (3 and 11) were obtained with a known protocol [14] by oxidation with tert-butyl hypochloride, albeit with quite poor yields. Excellent yields were observed in the preparation of sulfones 4 and 12, which was achieved with Eur. 2879 Scheme 4. Synthesis of 2,4-dimethylthiane derivatives. Conditions: a) MsCl, Et 3 N, CH 2 Cl 2 , 0°C, 45 min (quant.); b) Na 2 S, MeOH/H 2 O, reflux, 2 h (65 %); c) KMnO 4 , CH 2 Cl 2 /H 2 O, r.t., 16 h (94 %); d) BuLi, THF, 0°C to r.t., 30 min, then MeI, 0°C to r.t. (19: 17 %, 18: 30 %, diastereomerically pure); e) O 3 , CH 2 Cl 2 , -40°C to r.t., 2 h (67 %, d.r. = 5.8:1); f) P 4 S 10 , CDCl 3 .