Regio- and Stereoselective Synthesis of Sulfur-Bearing Four-Membered Heterocycles: Direct Access to 2,4-Disubstituted Thietane 1‑Oxides

Starting from readily available C2-substituted
thietane 1-oxides,
a straightforward synthesis of new C2,C4-disubstituted thietane 1-oxides
has been developed by using a lithiation/electrophilic trapping sequence.
The chemical and configurational stability of lithiated C2-substituted
thietane 1-oxides has been investigated as well as the stereochemical
implications for this process. The results demonstrate that a stereoselective
functionalization at the C2, C4 positions of a thietane is feasible,
leaving intact the four-membered ring.