Regiospecific Ring Opening of Epoxides with Cyanotrimethylsilane on Solid Bases: Reaction Features, and Role of Metal Cations of Solid Bases

Article abstract of DOI:10.1246/bcsj.64.1792

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.