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.