Regiospecific Ring Opening of Epoxides with Cyanotrimethylsilane on Solid Bases: Reaction Features, and Role of Metal Cations of Solid Bases
作者:Keisuke Sugita、Akihisa Ohta、Makoto Onaka、Yusuke Izumi
DOI:10.1246/bcsj.64.1792
日期:1991.6
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。