Lewis acid-promoted reaction of β,γ-unsaturated α,α-dimethoxy esters with silyl nucleophiles

• Published in: Tetrahedron letters Vol. 53; no. 34; pp. 4584 - 4587
• Main Authors: Sugimura, Hideyuki, Miyazaki, Hiiro, Makita, Yui
• Format: Journal Article
• Language: English
• Published: OXFORD Elsevier Ltd 22.08.2012; Elsevier
• Subjects: Chemistry; Chemistry, Organic; Hosomi–Sakurai allylation; Mukaiyama aldol reaction; Physical Sciences; Science & Technology; β,γ-Unsaturated α-keto esters; γ-Substituted α,β-unsaturated α-methoxy esters; γ-Substituted α,β-unsaturated α-methoxy esters; Hosomi–Sakurai allylation; MJMCJQJFWASTPE-MDZDMXLPSA-N; MIPHAOQRBGSWPY-XMHGGMMESA-N; MIPHAOQRBGSWPY-RGEXLXHISA-N; Mukaiyama aldol reaction; NQDKTVHZFUSWRF-KAMYIIQDSA-N; β,γ-Unsaturated α-keto esters; NQDKTVHZFUSWRF-SDNWHVSQSA-N; beta,gamma-Unsaturated alpha-keto esters; ENOLATE CLAISEN REARRANGEMENT; ASYMMETRIC-SYNTHESIS; DIELS-ALDER REACTIONS; ENANTIOSELECTIVE SYNTHESIS; ALPHA-KETO ESTERS; MUKAIYAMA-MICHAEL REACTIONS; C-H BONDS; Hosomi-Sakurai allylation; gamma-Substituted alpha,beta-unsaturated alpha-methoxy esters; FRIEDEL-CRAFTS ALKYLATION; STEREOCONTROLLED SYNTHESIS; CONJUGATE ADDITION
• ISSN: 0040-4039; 1873-3581
• DOI: 10.1016/j.tetlet.2012.06.078

The Lewis acid-promoted reaction of β,γ-unsaturated α,α-dimethoxy esters, which are easily prepared by the acetalization of β,γ-unsaturated α-keto esters, with silyl nucleophiles is presented. By employing trimethylsilyl enolate and allyltrimethylsilane as nucleophiles, the BF3-promoted reactions of a series of β,γ-unsaturated α,α-dimethoxy esters bearing aromatic and aliphatic substituents proceeded at the γ-position in an SN2′ manner to furnish γ-substituted α,β-unsaturated α-methoxy esters in good yields with high regioselectivity. In contrast, the reaction using trimethylsilyl cyanide predominantly occurred at the α-position, and the reaction of silyl hydride resulted in a mixture of α- and γ-regioisomers in favor of the γ-substitution products.