Consecutive β,β'-Selective C(sp3 )-H Silylation of Tertiary Amines with Dihydrosilanes Catalyzed by B(C6 F5 )3.

Tris(pentafluorophenyl)borane has been found to catalyze the two-fold C(sp3 )-H silylation of various trialkylamine derivatives with dihydrosilanes, furnishing the corresponding 4-silapiperidines in decent yields. The multi-step reaction cascade involves amine-to-enamine dehydrogenation at two alkyl residues and two electrophilic silylation reactions of those enamines, one inter- and one intramolecular.