Trityl tetrakis(pentafluorophenyl)borate: A sustainable precursor for multifunctional silylium Lewis acid organocatalysis

In response to the growing demand for sustainable chemistry, there has been a notable surge of interest in developing efficient, metal-free, and versatile organic acid catalysts capable of facilitating the synthesis of complex valuable molecules. In this context, a silylium ion (tricoordinate, trivalent silyl cations) combined with a weakly coordinating anion as an organocatalyst could operate as a highly potent promotor in multifunctional transformations. We summarize the recent developments of silylium Lewis acid catalysis, mainly induced by trityl tetrakis(pentafluorophenyl)borate ([Ph₃C]⁺[B(C₆F₅)₄]^–) as a highly efficient catalytic precursor. The neutral, moisture-tolerant, bench-stable, metal-free salt could successfully catalyze diverse categorized transformations such as (1) hydrosilylation of alkene and alkyne, (2) reduction of carbonyl and imine, (3) carbon–fluorine bond activation, and (4) carbon–carbon bond formation. Concise mechanistic elaborations on the appeared reactions are discussed.