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Paper | Special issue | Vol 99, No. 1, 2019, pp.145-170
Published online, 28th June, 2018
DOI: 10.3987/COM-18-S(F)5
CsF-Promoted Desilylation and Ring-Contraction Reaction of Electron-Deficient 3-Silyl-2H-chromenes to 2-Benzylbenzofurans

Kenta Tanaka, Mayumi Sukekawa, Mami Kishimoto, Yujiro Hoshino, and Kiyoshi Honda*

*Graduate School of Environment and Infomation Science, Yokohama National University, Tokiwadai 156, Hodogaya-ku, Yokohama 240-8501, Japan


The ring-contraction reaction of electron-deficient 3-silyl-2H-chromenes to 2-benzylbenzofurans under mild conditions was developed. CsF efficiently promoted the reaction at room temperature or 80 ºC to afford a variety of 2-benzylbenzofurans in good yields. 3-Silyl-2H-chromenes having strong electron-withdrawing groups smoothly afforded the desired products. The reaction is proposed to proceed through an allenyl intermediate or dyotropic rearrangement.