Silicon Lewis Acid Catalyzed [3+2] Cycloaddition Reactions of Hydrazones/Cyclopentadiene: Mild Access to Pyrazolidine Derivatives
作者:Alexandru Zamfir、Sebastian Schenker、Walter Bauer、Timothy Clark、Svetlana B. Tsogoeva
DOI:10.1002/ejoc.201100206
日期:2011.7
A first and fairly mild metal-free catalytic route was developed for the [3+2] cycloadditions of different N-acylhydrazones to cyclopentadiene, providing the synthetically andbiologically important five-membered cyclic compounds pyrazolidines. The reaction was successfully conducted in high yields (up to 99 %) with high diastereoselectivities (up to 98:2 dr) by using catalytic amounts of TMSOTf (trimethylsilyl
第一个相当温和的无金属催化路线被开发用于不同 N-酰基腙与环戊二烯的 [3+2] 环加成反应,提供合成和生物学上重要的五元环状化合物吡唑烷。通过使用催化量的 TMSOTf(三甲基甲硅烷基三氟甲磺酸酯)作为容易获得的路易斯酸性催化剂,该反应以高产率(高达 99%)和高非对映选择性(高达 98:2 dr)成功进行。实验结果得到了反应机理的 DFT 计算的支持。理论和实验非对映体过量值显示出良好的一致性,使计算成为预测这些和相关反应中选择性的有效工具。