The Total Synthesis of C-Glycosides with Completely Resolved Seven-Carbon Backbone Polyol Stereochemistry: Stereochemical Correlations and Access toL-Configured and Other Rare Carbohydrates
作者:H. Martin R. Hoffmann、Ralf Dunkel、Matthias Mentzel、Henning Reuter、Christian B. W. Stark
novo synthesis of a full set of hydroxymethyl C-glycosides from only two precursors is described. The seven-carbon target molecules contain five stereocentres and bridge the stereochemical gap between natural D-configured and non-natural L-configured series of hexoses. Key steps include hydroxylation, differential protection, stereoselective reduction and desymmetrization of 8-oxabicyclo[3.2.1]oct-6-enes
A series of 2-fluoro-8-oxabicyclo[3.2.1]octan-3-ones are prepared and tested as catalysts for alkene epoxidation with Oxone®. These catalysts provide trans-stilbene oxide with up to 83% ee, but the highest ee value is obtained with the monofluorinated ketone 2: both 2,2- and 2,4-disubstituted catalysts afford epoxide of lower ee.
A new class of chiral tetrahydropyran-4-one catalyst for asymmetric epoxidation of alkenes
作者:Alan Armstrong、Tomoki Tsuchiya
DOI:10.1016/j.tet.2005.08.112
日期:2006.1
A new class of chiral α-oxygenated-tetrahydropyran-4-ones for asymmetric epoxidation of alkenes using Oxone® is described, affording epoxides with up to 83% ee.