Palladium Catalyzed Oxidative Trifluoromethoxylation of Allyl C-H Bonds
As an important class of compounds, fluorine-containing organic compounds are widely used in medicine, pesticides, and functional materials. The direct functionalization of C-H bonds into fluorine atoms or fluorine-containing groups is a very efficient method for synthesizing such compounds. For the past few years, significant progress has been made in the fluorination, trifluoromethylation, and trifluoromethylthiolation reactions of C-H bonds. In contrast, the trifluoromethoxylation reaction based on CH bond activation, as the trifluoromethoxy anion is very unstable, it’s easy to decomposes into difluorophosgene and fluorine anion, and lacks an effective synthesis of trifluoromethoxy groups. The method of reagents, oxidation of the CH bond by trifluoromethoxylation has always been a problem.
Recently, the team of Liu Guosheng of the Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, reported that palladium catalyzes the trifluoromethoxylation of allylic C—H bonds, using CsOCF3 with good stability and poor solubility under mild conditions as The fluoromethoxyl source, in the presence of AgBF4, using phenylhydrazine as the oxidant, slowly releases AgOCF3 in the reaction system in the field, avoiding the problem that AgOCF3 will be decomposed in large quantities at the initial reaction, and highly selective synthesis of allyl trifluoromethoxy ether-based compounds can be achieved. It provides an efficient preparation method for synthesizing compounds containing OCF3.