Stereoselective Syntheses of β- l -FD4C and β- l -FddC

Stereocontrolled syntheses of two potent antiviral agents, β- l -FD4C and β- l -FddC, were accomplished both in 10-step sequences, with an overall yield of 27% and 25%, respectively. It is worthwhile to mention that the introduction of a phenylseleno moiety to the C-2α position of the lactone 4 can now be performed in a stereocontrolled fashion, providing the key intermediate 5 α in 75% yield.