Organocatalytic Enantioselective Synthesis of Tetrahydrofluoren-9-ones via Vinylogous Michael Addition/Henry Reaction Cascade of 1,3-Indandione-Derived Pronucleophiles

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• 作者：Lennart Möhlmann ; Geng-Hua Chang ; G. Madhusudhan Reddy ; Chia-Jui Lee ; Wenwei Lin
• 刊名：Organic Letters
• 出版年：2016
• 出版时间：February 19, 2016
• 年：2016
• 卷：18
• 期：4
• 页码：688-691
• 全文大小：301K
• ISSN：1523-7052

文摘

An unprecedented organocatalytic enantioselective vinylogous Michael addition/Henry cyclization cascade is presented for the synthesis of highly substituted tetrahydrofluoren-9-ones 3 employing novel 1,3-indandione-derived pronucleophiles 1a–g and nitroalkenes 2. Following a very simple protocol, a wide range of products were obtained in good to excellent yields and with excellent enantioinduction (43–98% yield, up to 98% ee). The reaction proceeded with excellent diastereocontrol despite the simultaneous generation of four stereogenic centers. Surprisingly, when 2-(1-phenylethylidene)-1H-indandione (1h) was used as a pronucleophile, no cyclization was observed, and only Michael addition adducts 4a–x were furnished in very good yields and excellent enantioselectivities.