Trifluoromethyl (CF3) groups are versatile structural motifs, since this entity is abundantly present in pharmaceuticals, agrochemicals and organic functional materials. More recently, a remarkable increase in FDA-approved drug molecules containing a CF3 group is noticed, because it significantly enhances molecular properties such as binding selectivity, liphophilicity and metabolic/chemical stability. This CF3 moiety is typically installed on arenes via cross-coupling reactions requiring expensive trifluoromethylating agents and stoichiometric amounts of homogeneous organometallic complexes/metal oxidants at elevated temperatures. Recently, homogeneous photoredox catalysis using Ru(bipy)3Cl2 as photocatalyst, has emerged as a promising alternative, since it is a mild and efficient approach for creating electrophilic °CF3 radicals. Nevertheless, the high cost and the laborious post synthetic separation of the homogeneous photoactive catalyst hamper their further application in large-scale processes and heterogeneous materials should be considered. Therefore, faujasite-type zeolite Y materials are of great interest due to its ability to entrap organometallic complexes in their supercages via ‘a-ship-in-a-bottle’ strategy. In this work, Ru(bipy)32+, is synthesized within the supercages of the faujasite type zeolite Y via a ‘ship-in-a-bottle’ method to produce a single-site heterogeneous catalyst for the trifluoromethylation of arenes using CF3SO2Cl at room temperature. The support material was carefully selected to provide suitable cage dimensions and the optimal Si/Al ratio to withstand the reaction conditions. The incorporation of the Ru(bipy)32+ into the supercages of the faujasite was confirmed by FTIR, UV-Vis and N2-physisorption experiments. Furthermore, the oxidation state and the local environment of the Ru-center was studied by XAS experiments. The performance of the single-site heterogeneous catalyst was tested for the trifluoromethylation of different arenes resulting in high yields (&gt;70%). Ultimately, the substrate scope was expanded towards pharmaceutically relevant substrates, such as uracil analogues.

Ru-bipyridine entrapped in the supercages of EMC-1 Faujasite as catalyst for the trifluoromethylation of arenes

ACS Spring 2022

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