A Chiral N, N′‐Dioxide–ZnII Complex Catalyzes the Enantioselective [2+2] Cycloaddition of Alkynones with Cyclic Enol Silyl Ethers. Issue 18 (5th April 2016)

• Record Type: Journal Article
• Authors: Kang, Tengfei; Ge, Shulin; Lin, Lili; Lu, Yan; Liu, Xiaohua; Feng, Xiaoming
• Is Part Of: Angewandte Chemie international edition. Volume 55:Issue 18(2016)
• Page Start: 5541
• Page End: 5544
• Publication Date: 2016-04-05
• Subjects: [2+2] cycloaddition -- asymmetric catalysis -- cycloaddition -- N, N′-dioxides -- synthetic methods; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201600801
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: A highly efficient enantioselective [2+2] cycloaddition between alkynones and cyclic enol silyl ethers was developed by using a chiral N, N′ ‐dioxide‐zinc(II) complex as a catalyst. This method functions well for a variety of terminal alkynes as well as cyclic enol silyl ethers, with good to excellent enantioselectivity (up to 97 % ee ). This is also the first successful example for the catalytic enantioselective [2+2] cycloaddition of internal alkynes with cyclic enol silyl ethers to give fully substituted cyclobutenes. Meanwhile, the desired cyclobutene product can easily be transformed into fused cyclobutane derivatives. Abstract : Fused cyclobutenes : The title reaction was realized by using a chiral N, N′ ‐dioxide–Zn(NTf2 )2 catalyst. The reaction functions well for a variety of terminal alkynes and cyclic enol silyl ethers, providing good to excellent enantioselectivity. Internal alkynes were utilized in this reaction to give fully substituted cyclobutenes. TBS= tert ‐butyldimethylsilyl.