Chiral Lewis Acid Catalyzed Asymmetric Cycloadditions of Disubstituted Ketenes for the Synthesis of β-Lactones and δ-Lactones

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• 作者：Xiaoyu Hao ; Xiaohua Liu ; Wei Li ; Fei Tan ; Yangyang Chu ; Xiaohu Zhao ; Lili Lin ; Xiaoming Feng
• 刊名：Organic Letters
• 出版年：2014
• 出版时间：January 3, 2014
• 年：2014
• 卷：16
• 期：1
• 页码：134-137
• 全文大小：277K
• ISSN：1523-7052

文摘

Highly diastereo- and enantioselective [2 + 2]- and [4 + 2]-cycloadditions of disubstituted ketenes were realized by chiral Lewis acid catalysis. A series of arylalkylketenes underwent the reaction smoothly with isatins and 尾,纬-unsaturated 伪-ketoesters, providing optically active 尾-lactones and 未-lactones with vicinal chiral centers in excellent yields (up to 99%) and enantioselectivities (up to 99% ee), as well as exclusively high diastereoselectivities under 0.2鈥? mol % catalyst loading.