Self-Condensation of Enaminodiones as a Method for Benzene Ring Construction: Synthesis of Diacyl-Substituted Phenols and Catechols.

A novel transition metal-free approach for the construction of the benzene core has been developed through self-condensation of available enaminodiones. Functionalized acyl-substituted phenols and catechols were obtained in 29-97% yields with high chemoselectivity under mild conditions. This base-promoted formal [4+2] annulation proceeds via cyclohexanone formation and involves the cascade transformation based on double Michael addition and aromatization (retro-Claisen cleavage and amine elimination).