Ti(III)-Catalyzed Cyclizations of Ketoepoxypolyprenes: Control over the Number of Rings and Unexpected Stereoselectivities

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• 作者：Sara P. Morcillo ; Delia Miguel ; Sandra Resa ; Ana Mart铆n-Lasanta ; Alba Mill谩n ; Duane Choquesillo-Lazarte ; Juan M. Garc铆a-Ruiz ; Antonio J. Mota ; Jos茅 Justicia ; Juan M. Cuerva
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：May 14, 2014
• 年：2014
• 卷：136
• 期：19
• 页码：6943-6951
• 全文大小：521K
• 年卷期：v.136,no.19(May 14, 2014)
• ISSN：1520-5126

文摘

We describe a new strategy to control the number of cyclization steps in bioinspired radical (poly)cyclizations involving epoxypolyenes containing keto units positioned along the polyene chain. This approach provides an unprecedentedly straightforward access to natural terpenoids with pendant unsaturated side chains. Additionally, in the case of bi- and tricyclizations, decalins with cis stereochemistry have been obtained as a consequence of the presence of the ketone. The preferential formation of cis-fused adducts was rationalized using DFT calculations. This result is completely unprecedented in biomimetic cyclizations and permits the access to natural terpenoids with this stereochemistry, as well as to non-natural analogues.