Asymmetric Annulation of Donor鈥揂cceptor Cyclopropanes with Dienes

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• 作者：Hao Xu ; Jiang-Lin Hu ; Lijia Wang ; Saihu Liao ; Yong Tang
• 刊名：Journal of the American Chemical Society
• 出版年：2015
• 出版时间：July 1, 2015
• 年：2015
• 卷：137
• 期：25
• 页码：8006-8009
• 全文大小：376K
• ISSN：1520-5126

文摘

An efficient [4 + 3] cycloaddition reaction of D鈥揂 cyclopropanes with dienes has been successfully developed. The reaction proceeds well with various dienolsilyl ethers in the presence of Lewis acid, delivering a variety of cycloheptenes and [n,5,0]carbobicycles with excellent stereoselectivity. The asymmetric version of this reaction is also realized using a newly designed chiral Cy-TOX ligand, providing a new approach to access optically active cycloheptenes and [n,5,0]carbobicycles. Mechanisic study reveals that the reaction involves a stepwise pathway, which undergoes an unusual ring opening of five-membered [3 + 2] intermediate and sequential intramolecular cyclization to afford the thermodynamically stable [4 + 3] annulation product.