Catalytic Asymmetric Synthesis of Chiral Dihydrobenzofurans through a Formal [4+1] Annulation Reaction of Sulfur Ylides and In Situ Generated ortho-Quinone Methides

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• 作者：Qing-Qing Yang and Wen-Jing Xiao
• 刊名：European Journal of Organic Chemistry
• 出版年：2017
• 出版时间：January 10, 2017
• 年：2017
• 卷：2017
• 期：2
• 页码：233-236
• 全文大小：759K
• ISSN：1099-0690

文摘

The first example of a catalytic asymmetric formal [4+1] annulation reaction between sulfur ylides and in situ generated ortho-quinone methides (o-QMs) is reported in this work. A C2-symmetric chiral urea was identified to be the best H-bonding catalyst, affording a wide range of chiral 2,3-dihydrobenzofurans in high yields and moderate enantioselectivities [70–98 % yields, up to 89:11 e.r. (enantiomeric ratio)].