1,1,3,3-四(全氟己基乙基)二锡氧烷二聚体在环氧化合物开环反应中的催化作用

采用氟碳-有机溶剂两相催化体系,考察了1,1,3,3-四(全氟己基乙基)二锡氧烷二聚体(1)在环氧化合物开环反应中的催化作用.结果表明,催化剂(1)在氟碳-有机溶剂两相体系中使环氧苯乙烯和甲醇的开环反应产率高达95%,¹³CNMR谱表明,开环反应的区域选择性为100%.在氟碳-有机溶剂两相催化体系中以一锅法制备了3-苯基丙酸2-甲氧基-2-苯乙醇酯,收率高,方法简便,催化剂几乎可以定量回收循环使用.     

Zirconyl nitrate mediated regioselective ring opening of epoxides and aziridines: an easy synthesis of β-nitrato-alcohols and -sulfonamides

Epoxides and aziridines are cleaved efficiently and regioselectively in the presence of zirconyl nitrate at room temperature to afford the corresponding β-nitrato-alcohols and -sulfonamides, respectively, in high yields.     

Aluminumdodecatungstophosphate (AlPW12O40) as a reusable Lewis acid catalyst: Facile regioselective ring opening of epoxides with alcohols, acetic acid and thiols

AlPW₁₂O₄₀ as a recyclable Lewis acid and stable solid compound was introduced for efficient ring opening of different epoxides with thiols, acetic acid, and primary, secondary, and tertiary alcohols. These processes were carried out at room temperature with high regio- and stereoselectivity.     

聚酯-聚醚嵌段共聚物同环氧树脂共混改性的研究

聚酯-聚醚多嵌段共聚物同少量的环氧树脂等共混,可以改善共混物作热熔胶使用时的剪切强度、剥离强度和热光老化性能。本文研究了共混条件,同时根据IR、DTA、TM和TG实验结果,提出了在熔融粘接过程中,环氧基同共聚物端羟、羧基反应的可能性。     

Iminosugars from α,β-epoxyamides. Part 2: Synthetic approach to hydroxylated pyrrolidine and azepane derivatives

This paper describes a new synthetic route towards hydroxylated pyrrolidines and azepane derivatives starting from chiral epoxyamides. The alternate transformations on a ribose derivative α,β-epoxyamide permit the construction of five or seven member rings leading to different precursors of homoiminosugars.     

Isotope effects and the mechanism of deoxygenation of epoxides with dichlorocarbene

The deoxygenation of styrene oxide with dichlorocarbene is studied by a combination of isotope effects and theoretical calculations. A normal ¹³C isotope effect of 1.016 is observed for the α-carbon of the styrene oxide but a surprising inverse isotope effect of 0.995 is observed at the β-carbon. This is indicative of a highly asynchronous process in which the C_α-O bond is broken without any progress in the breakage of C_β-O bond. Theoretical calculations support this interpretation. This coarctate reaction is formally concerted as it avoids involving a high-energy intermediate, but it appears uninfluenced by transition state aromaticity.     

Effect of HCl on the PPO assisted sol-gel synthesis of olivine-type Co2SiO4 ultrafine particles

Olivine-type Co₂SiO₄ ultrafine particles were synthesized by a sol-gel method using propylene oxide as a gelation agent. Owing to the high homogeneity of the intermediate gel precursor, the usage of this epoxide method results in a substantial reduction of calcination temperature and time as compared with the solid-state route, and a great reduction of calcination time as compared with other wet-chemistry routes. This high homogeneity is obtained by the usage of an appropriate amount of HCl, as a catalyst that matches the rate of hydrolysis of TEOS and the metal ions, allowing the formation of Si–O–Co bonds.     

Rapid and efficient ring opening of epoxides catalyzed by a new electron deficient tin(IV) porphyrin

The new electron deficient tin(IV) tetraphenylporphyrinato trifluoromethanesulfonate, [Sn^IV(tpp)(OTf)₂], was used as an efficient catalyst for the alcoholysis, hydrolysis and acetolysis of epoxides. Conversion of epoxides to thiiranes and acetonides were also performed efficiently in the presence of this catalyst.