Robust Synthesis of N‐Sulfonylazetidine Building Blocks via Ring Contraction of α‐Bromo N‐Sulfonylpyrrolidinones.

In the presence of potassium carbonate various nucleophiles such as aliphatic alcohols, phenols, and anilines, but no thiols or benzylamine, are efficiently incorporated into N-sulfonylpyrrolidinones to form azetidine derivatives.