Silica‐Supported Silver Nitrate as a Highly Active Dearomatizing Spirocyclization Catalyst: Synergistic Alkyne Activation by Silver Nanoparticles and Silica

Abstract

Abstract Silica‐supported AgNO 3 (AgNO 3 –SiO 2 ) catalyzes the dearomatizing spirocyclization of alkyne‐tethered aromatics far more effectively than the analogous unsupported reagent; in many cases, reactions which fail using unsupported AgNO 3 proceed effectively with AgNO 3 –SiO 2 . Mechanistic studies indicate that this is a consequence of silver nanoparticle formation on the silica surface combined with a synergistic effect caused by the silica support itself. The remarkable ease with which the reagent can be prepared and used is likely to be of much synthetic importance, in particular, by making nanoparticle catalysis more accessible to non‐specialists.