Scheme 4. Proposed activation mechanism and mechanistic studies. (a) Metal tetrafluoroborate pre-catalyst activation strategy from reaction with silane reagents to generate a low oxidation-state active catalyst. (b) Interaction of tetrabutylammonium tetrafluoroborate and phenylsilane for the reduction of 4-fluorobenzaldehyde, suggestive of hydride formation. (c) Attempted radical inhibition experiments with radical trapping reagents.
