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.
利用固态酸和碱进行
环氧化物与Me3SiCN开环反应的新尝试已被研究。与均相催化剂相比,固态强碱如
氧化钙和
氧化镁能更有效地催化
环氧化物与Me3SiCN的区域选择性和
化学选择性开环反应。在
氧化钙和
氧化镁存在下,不对称
环氧化物与Me3SiCN的反应通过
氰离子对次级环氧碳的区域和立体选择性攻击,高产率地生成了3-三甲基
硅氧基烷腈。此外,在
氧化钙存在下,2,3-环氧-1-醇衍
生物被
氰离子选择性地转化为相应的C-3开环产物,且未形成异
氰化物。研究提出,
氧化钙作为一种双功能催化剂,其晶格氧化物阴离子活化Me3SiCN,同时
钙离子作为
路易斯酸位点促进环氧醇的开环反应。