Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Department of Chemistry, Zhejiang Normal University, 688 Yingbin Road, Jinhua, 321004, P. R. China.
Nat Commun. 2022 Aug 12;13(1):4734. doi: 10.1038/s41467-022-32467-x.
[3+2] Cycloaddition is a step- and atom-economic method for the synthesis of five-membered rings. Despite the great success of 1,3-dipolar cycloadditions, the radical [3+2] annulation of alkynes remains a formidable challenge. Herein, a photoinduced decatungstate-catalyzed [3+2] cycloaddition of various internal alkynes using abundant aliphatic aldehydes as a three-carbon synthon is developed, producing elaborate cyclopentanones in 100% atom economy with excellent site-, regio-, and diastereoselectivity under mild conditions. The catalytic cycle consists of hydrogen atom abstraction from aldehydes, radical addition, 1,5-hydrogen atom transfer, anti-Baldwin 5-endo-trig cyclization, and back hydrogen abstraction. The power of this method is showcased by the late-stage elaboration of medicinally relevant molecules and total or formal synthesis of (±)-β-cuparenone, (±)-laurokamurene B, and (±)-cuparene.
[3+2]环加成是一种用于合成五元环的步骤经济性和原子经济性方法。尽管 1,3-偶极环加成取得了巨大的成功，但炔烃的自由基[3+2]环化仍然是一个巨大的挑战。在此，开发了一种光诱导的 decatungstate 催化的[3+2]环加成反应，使用丰富的脂肪醛作为三碳合成子，与各种内部炔烃反应，在温和条件下以 100%的原子经济性、优异的位置、区域和非对映选择性生成精致的环戊酮。催化循环包括从醛中提取氢原子、自由基加成、1,5-氢原子转移、反 Baldwin 5-endo-trig 环化和回氢提取。该方法的强大之处在于对具有医学相关性的分子的后期修饰以及（±）-β-古巴烯酮、（±）-劳罗卡芒烯 B 和（±）-古巴烯的全合成或形式合成。
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