HfCl<sub>4</sub>-Catalyzed [4 + 2] Cycloaddition of β,γ-Unsaturated α-Keto Esters with Alkynes
作者:Depeng Duan、Huixin Qiu、Mengdie Tang、Ran Song、Wen Si、Daoshan Yang、Jian Lv
DOI:10.1021/acs.joc.2c00007
日期:2022.4.15
Herein we report Lewis acid HfCl4-catalyzed [4 + 2] cycloaddition between β,γ-unsaturated α-keto esters and various symmetric or unsymmetric alkynes, giving the desired polysubstituted 4H-pyrans in up to 98% yield and with excellent regioselectivity (>99:1) via a vinyl carbocation under mild conditions.
在此,我们报道了路易斯酸 HfCl 4催化的 β,γ-不饱和 α-酮酯和各种对称或不对称炔烃之间的 [4 + 2] 环加成反应,以高达 98% 的产率和优异的区域选择性得到所需的多取代 4 H-吡喃(>99:1) 在温和条件下通过乙烯基碳正离子。