3,4,5-Trimethylphenol and Lewis Acid Dual-Catalyzed Cascade Ring-Opening/Cyclization: Direct Synthesis of Naphthalenes

A 3,4,5-trimethylphenol and Lewis acid dual-catalyzed cascade reaction of donor–acceptor (D–A) cyclopropanes via ring-opening and cyclization is developed. In this reaction, a phenolic compound was used as a covalent catalyst for the first time. Additionally, control experiments proved that 3,4,5-trimethylphenol completed the catalytic cycle by accomplishing the C–C bond cleavage. Using this strategy, a wide variety of substituted naphthalenes has been synthesized from D–A cyclopropanes in moderate to high yields under mild conditions