Post-Ugi cyclization approach for transition metal-free synthesis of Azetidine derivatives

A novel, metal-free strategy has been developed for the efficient synthesis of unique azetidine derivatives via a post-Ugi cyclization. This method involves generating 4-component Ugi adducts by reacting aldehydes, isocyanides, primary propargylamine, and 2-(phenylamino) benzoic acid. In the subsequent post-Ugi cyclization, azetidine derivatives are synthesized through a nucleophilic attack of a carbanion on the alkyne, followed by an intramolecular cyclization that forms a new carbon‑carbon bond.