Base-Free and Catalyst-Free Synthesis of Functionalized Dihydrobenzoxazoles via Vinylogous Carbonate to Carbamate Rearrangement.

An unexpected, catalyst-free, and base-free intramolecular cyclization of N-aryloxyacrylate aldimines, under thermal conditions leading to the synthesis of functionalized dihydrobenzoxazoles, is reported. The reaction features a unique rearrangement of vinylogous carbonates to vinylogous carbamates resulting in a new carbon-oxygen and carbon-nitrogen bond construction. The reaction tolerates a broad range of functional groups and the desired products are formed in moderate to good yields.