Combinations of Ethers and B(C6F5)3 Function as Hydrogenation Catalysts

摘要

Since its discovery in the 1960s, the electrophilic borane B(C6F5), has been used extensively in catalysis. Perhaps best-known as a co-catalyst or activator for ethylene polymerization. this highly electrophilic species has also found applications within a variety of Lewis acid-catalyzed transformations. For example, in the early 2000s, Piers, Gevorgyan, and co-workers pioneered its use in hydrosilylation chemistry. Since then, others have developed applications in hydrostannylation, silane dehydrocoupling, and silicone production and derivatization. More recently, this elec-trophile has been exploited in "frustrated Lewis pair" (FLP) chemistry, acting as the Lewis acid partner in conjunction with bases to activate a wide variety of small molecules, including H2, CO2, olefins, alkynes, N2O, and NO,among others. The application of this borane in FLP or "metal-free" hydrogenation catalysis has drawn much attention. Initially, the substrates were limited to imines, protected nitriles, and aziridines. Subsequently, enamines and silylenol ethers were also shown to be viable substrates for FLP reductions.