Stereoselective C9 Arylation and Vinylation of <i>Cinchona</i> Alkaloids
作者:Przemysław J. Boratyński、Ilona Turowska-Tyrk、Jacek Skarżewski
DOI:10.1021/ol7026625
日期:2008.2.1
A simple and efficient method for the highly stereoselective C-9 arylation and vinylation of Cinchona alkaloids was developed. Both 9s- and 9R-chloroquinine with PhMgBr yielded 9S-phenylquinine (X-ray structure). The reactions with various aryl and vinyl Grignard reagents resulted in the series of 9S-aryl and vinyl alkaloid derivatives. The stereochemical outcome was rationalized by coordination of the magnesium atom to the quinuclidine nitrogen, thus directing the nucleophilic attack at the C-9 stereogenic center.
Tricyclic Quaternary Ammonium Salts Derived from <i>Cinchona</i> Alkaloids
作者:Przemysław J. Boratyński、Rafał Kowalczyk、Anna Kobylańska、Julia Bąkowicz
DOI:10.1021/acs.joc.6b02348
日期:2016.12.16
bridgehead nitrogen atoms are rare but an interesting class of compounds. Chiral quinuclidine derivative salts with fused five and six-membered rings (X-ray) were obtained via modification of Cinchona alkaloids. The ease of ring formation was dependent on its size, while even mild activation sufficed to close the five membered ring. On the other hand the systems with fused benzene and a six-membered ring