Tertiary Amine‐Catalyzed Stereoretentive Multi‐Component Cascade Reaction of Carboxylic Acids: Facile Synthesis of Cyclic Ureas/Urethanes

Comprehensive Summary Herein, we developed a tertiary amine‐catalyzed stereoretentive multi‐component cascade reaction featuring an amidation/[4 + 1] annulation/decarboxylation/Curtius rearrangement/[2 + n ] annulation sequence. This metal‐free and step‐economic method provided a broad range of cyclic ureas/urethanes in green solvent under mild conditions without employing explosive and toxic reagents. Importantly, this reaction generated isocyanates in situ under catalytic conditions via a decarboxylation/Curtius rearrangement process of dioxazolones.