Lewis Acid Rather than Bronsted Acid Sites of Montmorillonite K10 Act as a Powerful and Reusable Green Heterogeneous Catalyst for Rapid Cyanosilylation of Ketones

A practical green protocol was developed for highly efficient cyanosilylation of various ketones catalyzed by commercial montmorillonite K10, with excellent isolated yields (91-99%). The catalyst can be used as received, and its catalytic strength can be easily restored without loss of activity. Investigations of catalyst recycling and of the active catalytic sites indicated that Lewis acid sites were mainly responsible for the cyanosilylation of ketones.