AbstractIn this paper, we report BF3 ⋅ OEt2 as a catalyst to shuttle equivalents of HF from a fluoroalkane to an alkyne. Reactions of terminal and internal aliphatic alkynes led to formation of difluoroalkane products, while diarylalkynes can be selectively converted into fluoroalkenes. The method tolerates numerous sensitive functional groups including halogen, protected amine, ester and thiophene substituents. Mechanistic studies (DFT, probe experiments) suggest the catalyst is involved in both the defluorination and fluorination steps, with BF3 acting as a Lewis acid and OEt2 a weak Lewis base that mediates proton transfer. In certain cases, the interconversion of fluoroalkene and difluoroalkane products was found to be reversible. The new catalytic system was applied to demonstrate proof‐of‐concept recycling of poly(vinylidene difluoride).
摘要 在本文中,我们报告了 BF3 ⋅ OEt2 作为催化剂将等当量的 HF 从氟烷烃穿梭到炔烃的情况。末端和内部脂肪族炔烃的反应可形成二氟烷烃产物,而二芳基炔烃则可选择性地转化为氟烯烃。该方法可容忍多种敏感官能团,包括卤素、受保护的胺、酯和噻吩取代基。机理研究(DFT、探针实验)表明,催化剂参与了脱氟和氟化两个步骤,其中 BF3 起着路易斯酸的作用,而 OEt2 则是介导质子转移的弱路易斯碱。在某些情况下,氟烯烃和二氟烷烃产物的相互转化是可逆的。新催化系统被用于演示聚偏二氟乙烯的概念验证回收。