[3+ 4] Annulation of α, β-Unsaturated Acylsilanes with Enolates of α, β-Unsaturated Methyl Ketones: Scope and Mechanism

…, M Takeda, Y Okamoto, T Sato, E Yoshii…

Index: Takeda, Kei; Nakajima, Akemi; Takeda, Mika; Okamoto, Yasushi; Sato, Taku; Yoshii, Eiichi; Koizumi, Toru; Shiro, Motoo Journal of the American Chemical Society, 1998 , vol. 120, # 20 p. 4947 - 4959

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Citation Number: 53

Abstract

Reactions of the E and Z isomers of (β-(trimethylsilyl) acryloyl)(tert-butyl) dimethylsilanes with lithium enolate of α, β-unsaturated methyl ketones at-80 to-30° C afford cis-5, 6-and trans-5, 6-disubstituted 3-cyclohepetenones, respectively. The same [3+ 4] annulation is observed in the reaction of (β-(tri-n-butylstannyl) acryloyl) silanes. The annulation products are readily transformed into 4-cycloheptene-1, 3-dione by treatment with NBS or mCPBA. ...