کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1349461 | 980400 | 2009 | 4 صفحه PDF | دانلود رایگان |
Dimeric anthracenyldimethyl-derived Cinchona ammonium salts are used as chiral organocatalysts in 1–10 mol % for the enantioselective conjugate addition of 2-alkoxycarbonyl-1-indanones to β-unsubstituted Michael acceptors. The corresponding adducts bearing a new all-carbon quaternary center were usually obtained in high yield and with up to 94% ee when using ammonium salts derived from quinidine and its pseudoenantiomer quinine as organocatalysts. These catalysts can be almost recovered quantitatively by precipitation in ether and reused.
Figure optionsDownload as PowerPoint slide
α,α′-Bis(quininium)-9,10-dimethylanthracene dichlorideC56H60Cl2N4O4[α]D25=-444 (c 0.5, CHCl3)Source of chirality: (−)-quinine
α,α′-Bis(quininium)-9,10-dimethylanthracene ditetrafluoroborateC56H60B2F8N4O4[α]D25=-112 (c 0.1, CHCl3)Source of chirality: (−)-quinine
α,α′-Bis(quininium)-9,10-dimethylanthracene dihexafluorophosphateC56H60F12N4O4P2[α]D25=-35 (c 0.1, CHCl3)Source of chirality: (−)-quinine
α,α′-Bis(quinidinium)-9,10-dimethylanthracene dichlorideC56H60Cl2N4O4[α]D25=+339 (c 0.5, CHCl3)Source of chirality: (+)-quinidine
Journal: Tetrahedron: Asymmetry - Volume 20, Issue 23, 11 December 2009, Pages 2651–2654