Search results for "SILP"
showing 2 items of 2 documents
Syntheses of (+)-alismoxide and (+)-4-epi-alismoxide.
2006
The first total syntheses of (+)-alismoxide and (+)-4-epi-alismoxide are reported. Formal chemo-, regio-, and stereoselective addition of water to 10alpha-acetoxy-1alphaH,5betaH-guaia-3,6-diene afforded the target compounds after reduction. The absolute stereochemistry of (+)-alismoxide has been established. The low [alpha](D) +8.6 value indicates that significant amounts of alismoxide result from biosynthetic processes. Furthermore, the structure of the natural guaienediol isolated from Silphium perfoliatum has been corrected to (-)-alismoxide.
Water-Tolerant Trifloaluminate Ionic Liquids: New and Unique Lewis Acidic Catalysts for the Synthesis of Chromane
2018
The first example of triflometallate ionic liquids, named in analogy to chlorometallate ionic liquids, is reported. Trifloaluminate ionic liquids, synthesised from 1-alkyl-3-methylimidazolium triflates and aluminium triflate, were characterised by multinuclear NMR spectroscopy and FT-IR spectroscopy, revealing the existence of oligonuclear, multiply-charged trifloaluminate anions, with multiple bridging triflate modes. Acceptor numbers were determined to quantify their Lewis acidity, rendering trifloaluminate ionic liquids as medium-strength Lewis acids (AN = ca. 65). Used as acidic catalysts in the cycloaddition of 2,4-dimethylphenol and isoprene (molar ratio 2:1) to prepare chromane, trif…