Elemental Sulfur-Promoted Benzoxazole/Benzothiazole Formation Using a C═C Double Bond as a One-Carbon Donator.

An efficient method to assemble diverse benzoxazoles/benzothiazoles in good yields was developed via oxidative cyclization with 2-aminothiophenols or 2-iodoanilines as raw materials. In this protocol, elemental sulfur was used as the effective oxidant and C atoms on the C═C double bond were introduced as a one-carbon donator.