Nucleophilic trifluormethylation of aryl boronic acid under heterogeneous Cu(INA)2 catalysis at room temperature: The catalytic copper-based protocol

Abstract Herein, we described the first heterogeneous and catalytic protocol for nucleophilic trifluoromethylation of aryl boronic acids. In particular, the synthesized metal-organic framework copper isonicotinate Cu(INA) 2 [INA = 1,4-(NC 5 H 4 CO 2 )] exhibited exceptional catalytic activity toward the trifluoromethylation of boronic acids. Optimal conditions involve the use of Cu(INA) 2 catalyst (30% mol), nucleophilic trifluoromethyltrimethylsilane (TMSCF 3 ) and CsF reagent in 1,2-dichloroethane (DCE) solvent at room temperature in 2 h. Molecular oxygen was employed as teminal oxidant. Noteworthily, reported conditions for same reactions required stoichiometric amount of homogeneous copper salts. Additionally, preliminary investigation of structure/activity relationship supported that weak interaction between copper centers and the presence of free carboxylate oxygen atoms within the network structure favored the trifluoromethylation. Subsequently, Cu(INA) 2 possessed higher activity than other copper-based homogeneous/heterogeneous catalysts and other MOFs catalysts. Leaching tests confirmed the heterogeneity of Cu(INA) 2 during reaction. Thus, almost similar reaction yield was still obtained at 6 th run.