Several derivatives were further characterised by X-Ray diffraction analysis of single crystals (2a, 3aa, 3ac, and 5aa, Scheme 1 boxed). Thietanol 2a showed a puckered thietane dioxide ring (29.4º) towards the hydroxyl group, suggestive of an intramolecular H-bond. On the other hand, diarylthietane dioxides were less puckered (3aa 14.0º; 3ac 16.9º) and the toluene sulfide derivative 5aa displayed a planar thietane dioxide ring (1º puckering angle). The dihedral conformation about the thietane-C-S bond is such that the tolyl group is aligned to the thietane S=O.