De novo asymmetric syntheses and biological evaluation of SL0101 and its enantiomer via a palladium-catalyzed glycosylation

ORGN 676

Bulan Wu,, Department of Chemistry, West Virginia University, Morgantown, WV 26506 and George A. O'Doherty,, C. Eugene Bennett Department of Chemistry, West Virginia University, 284 Prospect Street, 217 Clark Hall of Chemistry, WVU, Morgantown, WV 26506-6045.
The enantioselective syntheses of naturally occurring kaempferol glycoside SL0101 and its analogues, as well as their enantiomers, have been achieved in 7-10 steps. The routes rely upon a diastereoselective palladium-catalysed glycosylation, ketone reduction, and dihydroxylation to introduce the rhamno-stereochemistry. The asymmetry of the sugar moiety of these kaempferol glycosides was derived from Noyori reduction of a furanketone. An acetyl group shift from an axial (C-2) to equatorial position (C-3) under basic conditions was also described.