Catalytic Access to Bridged Sila‑<i>N</i>‑heterocycles from Piperidines via Cascade sp³ and sp² C–Si Bond Formation

Described herein is the development of an unprecedented route to bridged sila-N-heterocycles via B­(C6F5)3-catalyzed cascade silylation of N-aryl piperidines with hydrosilanes. Mechanistic studies indicated that an outer-sphere ionic path is operative to involve three sequential catalytic steps having N-silyl piperidinium borohydride as a resting species: (i) dehydrogenation of the piperidine ring, (ii) β-selective hydrosilylation of a resultant enamine intermediate, and (iii) intramolecular dehydrogenative sp2 C–H silylation.