PREPARATION OF AN ENANTIOMERIC MIXTURE OF ERYTHRO AND THREO LACTONES

摘要

ABSTRACTThe present invention provides a process forpreparing lactone intermediates to 2',2'-difluoronucleo-sides whereby reversion back to the lactone's open chainprecursor is minimized and the desired erythro enantiomercan be selectively isolated from an enantiomeric mixtureof erythro and threo lactones in crystalline form. Alsoprovided is a process for producing 2'-deoxy-2',2'-difluoronucleosides in about a 1:1 .alpha./.beta. anomeric ratio,and processes for selectively isolating .beta.-2'-deoxy-2',2'-difluorocytidine, or an organic or inorganic acid addi-tion salt thereof, from the 1:1 .alpha./.beta. mixture.