The Friedel-Crafts reaction of homochiral pyrrole derivatives with α,β-unsaturated esters catalyzed by metal triflates furnished conjugate addition products. The best yields were obtained by using yttrium triflate and methyl 4-phenyl-2-oxobut-3-enoate (2a). The addition worked regioselectively at C-5 of pyrrole. The diastereoisomers were separated by column chromatography.
在
金属
三氟甲磺酸盐催化下,纯手性
吡咯衍
生物与α,β-不饱和酯发生傅克反应,生成共轭加成产物。使用
三氟甲磺酸钇和 4-苯基-2-氧代丁-3-烯酸甲酯 (2a) 获得了最佳产率。该加成在
吡咯的 C-5 处区域选择性地起作用。通过柱色谱法分离非对映异构体。