Beyond Hydrofunctionalisation: A Well-Defined Calcium Compound Catalysed Mild and Efficient Carbonyl Cyanosilylation.

Organocalcium compounds have been reported as efficient catalysts for various transformations, for cases in which one of the substrates contained an E-H (E=B, N, Si, P) bond. Here, we look at the possibility of employing an organocalcium compound for a transformation in which none of the precursors has a polar E-H bond. This study demonstrates the utilization of a well-defined amidinatocalcium iodide, [PhC(NiPr)2 CaI] (1) for cyanosilylation of a variety of aldehydes and ketones with Me3 SiCN under ambient conditions without the need of any co-catalyst. The reaction mechanism involves a weak adduct formation between 1 and Me3 SiCN leading to the activation of the Si-C bond, which subsequently undergoes σ-bond metathesis with a C=O moiety. Such a mechanistic pathway is unprecedented in alkaline earth metal chemistry. Experimental and computational studies support the mechanism.