Stereoselective Construction of Halogenated Quaternary Stereogenic Centers via Catalytic Asymmetric Diels−Alder Reaction

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• 作者：Kazutaka Shibatomi ; Kentaro Futatsugi ; Fumito Kobayashi ; Seiji Iwasa ; Hisashi Yamamoto
• 刊名：Journal of the American Chemical Society
• 出版年：2010
• 出版时间：April 28, 2010
• 年：2010
• 卷：132
• 期：16
• 页码：5625-5627
• 全文大小：248K
• 年卷期：v.132,no.16(April 28, 2010)
• ISSN：1520-5126

文摘

Highly enantioselective Diels−Alder reactions of α-halo-α,β-unsaturated ketones with Lewis acid-activated chiral oxazaborolidine 1 are described. The reaction with α-fluoroenones provided the corresponding cyclohexane derivatives having a fluorinated quaternary stereogenic center with up to 99% de and 94% ee. The reaction with α-bromo cyclic enones provided the corresponding bromo bicyclic adducts with up to 99% de and 95% ee. A brominated cis-fused bicyclic adduct derived from 2-bromocyclopenten-1-one and Dane’s diene was converted to the trans-fused bicyclic system via reductive alkylation with the bulky aluminum reagent aluminum tris(2,6-diphenylphenoxide) (ATPH). With this process, formal syntheses of (+)-estrone and norgestrel have been demonstrated.