Solid Acid and Base-Catalyzed Cyanosilylation of Carbonyl Compounds with Cyanotrimethylsilane

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Abstract
A new attempt was investigated to utilize inorganic solid acids and bases for the promotion of the reaction of cyanotrimethylsilane (Me3SiCN) with carbonyl compounds. Strongly acidic solids, such as Sn4+ ion-exchanged montmorillonite (Sn-Mont) and Fe3+ ion-exchanged montmorillonite (Fe-Mont), as well as basic solids, such as calcium fluoride (CaF2), hydroxyapatite (HAp), calcium oxide (CaO), and magnesium oxide (MgO), catalyzed the reaction of Me3SiCN with aldehydes and ketones to afford the corresponding 2-(trimethylsiloxy)alkanenitriles in good yields. The reactions of dimethyl acetals with Me3SiCN in the presence of solid acids afforded 2-methoxyalkanenitriles. In cyanosilylations of α,β-unsaturated ketones two kinds of adducts were produced selectively, depending on the use of a solid acid or a solid base: 1,4-Adducts (trimethylsilyl enol ether forms) were selectively obtained in the presence of strong solid acids, such as Fe-Mont and Sn-Mont, while 1,2-adducts (trimethylsilyl ether forms) were predominantly formed in the presence of solid bases, such as HAp, CaO, and MgO. The solid acids and bases realized higher activities and selectivities in the cyanosilylation than did conventional homogeneous catalysts.