ENANTIOISOMERS AND DIASTEREOISOMERS OF -5-(2,3-DIDEOXY-5-O-TRITYLRIBOFURANOSYL)PYRIMIDINE - 2',3'-DIDEOXY PYRIMIDINE C-NUCLEOSIDES BY PALLADIUM-MEDIATED GLYCAL AGLYCON COUPLING

Newly available enantiomeric 2,3-dideoxy glycals, (5S)- and (5R)-4,5-d ihydro-5-[(triphenylmethoxy)-methyl] furans and 2,4-dimethoxy-5-iodopy rimidine undergo palladium-mediated coupling by two different, complem entary procedures to form enantiomeric pairs of (2',3'-dideoxy-2',3'-d idehydrofuranosyl)- and (2',3'-dideoxy-3',4'-didehydrofuranosyl)pyrimi dine C-nucleosides. Stereoselective reductions of the carbohydrate uns aturations produce all four enantio- and diastereoisomers of 5-(2,3-di deoxy-5-O-tritylribofuranosyl)pyrimidine. The facile two-step synthese s of 2',3'-deoxy C-nucleosides which involves preparation of a D-serie s C-nucleoside from an L-series glycal (and vice versa) represents a n ew strategy for C-nucleoside synthesis.