Cationic silicon Lewis acids in catalysis


Silylium ions, or, to be more precise, donor-stabilized silylium-ion-like species, were once only the domain of computational and structural chemists. This was mainly due to the difficulties in generating and isolating these reactive species in a condensed phase. Even chemists focused on reactivity stayed away from such delicate ions. The state of affairs has changed in recent years as methods for their preparation have become more accessible and strategies for their stabilization more effective. Silylium ions have high electrophilicity, oxophilicity and fluorophilicity that have seen them emerge as useful catalysts, including for unique transformations not accessible to metal catalysts. This Perspective aims to provide a concise and conceptual summary of breakthroughs in this emerging area.

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Fig. 1: Classification and examples of silylium ions.
Fig. 2: Preparation of silylium ions.
Fig. 3: Silylium ions as catalysts in Diels–Alder reactions.
Fig. 4: Silylium ions as catalytic facilitators.
Fig. 5: Silylium ions as reagents for organic reactions.


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J.C.L.W. gratefully acknowledges the Alexander von Humboldt Foundation for a Theodor Heuss Fellowship (2018–2019). M.O. is indebted to the Einstein Foundation Berlin for an endowed professorship.

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Correspondence to Martin Oestreich.

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Walker, J.C.L., Klare, H.F.T. & Oestreich, M. Cationic silicon Lewis acids in catalysis. Nat Rev Chem 4, 54–62 (2020).

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