Copper-Catalyzed [4+2] Annulation of Oxetan-3-ols and Benzene-1,2-diols for the Synthesis of Benzodioxanes.

Annulation reactions based on oxetanes are important strategies for constructing heterocyclic compounds. In this paper, a Cu-catalyzed formal [4+2] annulation reaction between oxetan-3-ols and benzene-1,2-diols was developed, and a series of benzodioxane compounds were successfully synthesized. The activation of oxetan-3-ols with a trichloroacetimidate group was the key to the success of the reaction, which made the C-O bond of oxetan-3-ols easier to break. Under the copper catalyst, benzene-1,2-diols could efficiently undergo tandem nucleophilic attacking and ring-opening reactions with oxetan-3-ols for the synthesis of target benzodioxanes. In addition, the hydroxymethyl group reserved in the product was verified to have potential application value in synthetic transformations.