Frustrated Lewis pair‐catalyzed hydrogenation of unactivated alkenes with sterically hindered 9‐phosphatriptycenes

The frustrated Lewis pair-catalyzed hydrogenation of unactivated alkenes with H2 is reported. The weak Lewis basicity and high steric hindrance of ortho-substituted 9-phosphatriptycene derivatives is taken as an advantage to catalyze this reaction in combination with tris(pentafluorophenyl)borane. A scope of unsaturated substrates is described. The thermodynamics and kinetics of hydrogenation investigated by density functional theory show that the protonation of the olefin by the strongly acidic phosphonium cation is the critical step of the reaction.