Conformational analysis of thiolane-1-amides: an x-ray study of thiolane-1-tosylimide and diastereoisomeric 2-alkylthiolane-1-(arylsulphonyl)imides

摘要: Abstract The molecular structures of thiolane-, trans-2-methylthiolane-, trans-2-ethylthiolane- and cis-2-tert-butylthiolane-1-tosylimide that cis-2-methylthiolane-1-(p-nitro-phenylsulphonyl)imide were investigated by X-ray diffraction. results confirmed our earlier 13C-NMR assignments configurations. Direct evidence was obtained for ring geometry conformational preference substituents cyclic sulphilimines compared with analogous sulphoxides sulphonium salts. It has been found the electron-withdrawing bulky NTs (N-tosyl) group is pseudoaxial in thiolane-1-tosylimide. conformations 1,2-disubstituted thiolanes are controlled steric repulsion between 1-(arylsulphonyl)imino 2-alkyl groups, which 1-axial 2-equatorial cis derivatives, 1-endo-isoclina 2-exo-isoclinal trans isomers. 2-tert-butyl C4/C5 atoms almost antiperiplanar. In connection conformation S-tosylimino part, rotations about SIVN, NSVI SVICar bonds analysed, deviations from a SIV-symmetric “Koch-Moffitt's case IIa conjugation” interpreted terms stereoelectronic effects. Changes SIVC, SVIN SVIO bond lengths also rationalized.