Enantioselective Ring Opening of<i>meso</i>-Epoxides with Silicon Tetrachloride Catalyzed by Pyridine<i>N</i>-Oxides Fused with the Bicyclo[3.3.1]nonane Framework
作者:Algirdas Neniškis、Sigitas Stončius
DOI:10.1002/ejoc.201500762
日期:2015.10
chiral Lewis basic organocatalysts that contain pyridine N-oxide moieties fused with the bicyclo[3.3.1]nonane framework is reported. The obtained pyridine N-oxides were employed as catalysts in the enantioselective ring opening of meso-epoxides with silicon tetrachloride. Derivative 1b endowed with two 2,4-diaryl-substituted pyridine N-oxide moieties proved to be a particularly effective catalyst for desymmetrization
报道了新的手性路易斯碱性有机催化剂的合成,该催化剂含有与双环 [3.3.1] 壬烷骨架稠合的吡啶 N-氧化物部分。所得吡啶N-氧化物用作中间环氧化物与四氯化硅对映选择性开环的催化剂。具有两个 2,4-二芳基取代的吡啶 N-氧化物部分的衍生物 1b 被证明是一种特别有效的催化剂,可用于降冰片烯氧化物 16i 的去对称化,以提供前所未有的 96% ee 的 Wagner-Meerwein 重排产物 20i。双功能同源物 3 带有 4-芳基取代基,与脂环族环氧化物底物表现出中等至高水平的不对称诱导(47-88% ee)。