1991 Volume 64 Issue 6 Pages 1792-1799
A new attempt of utilizing solid acids and bases for ring opening of epoxides with Me3SiCN was investigated. Solid strong bases such as calcium oxide and magnesium oxide catalyzed the regio- and chemoselective ring opening of epoxides with Me3SiCN much more effectively than homogeneous catalysts. On CaO and MgO, the reactions of unsymmetrical epoxides with Me3SiCN afforded 3-trimethylsiloxyalkanenitriles in high yields through regio- and stereoselective attack of cyanide ion on the less substituted epoxycarbon. Additionally, on CaO, 2,3-epoxy-1-alkanol derivatives were selectively converted to the corresponding C-3 opened products by the attack of cyanide ion. In these cases no isocyanides were formed. It was suggested that CaO acted as a bifunctional catalyst; the lattice oxide anions of CaO activated Me3SiCN, and simultaneously calcium ions promoted the ring opening of epoxyalkanol as Lewis acid sites.
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