Stereocontrolled syntheses of two potent antiviral agents, beta-L-FD4C
and beta-L-FddC, were accomplished both in 10-step sequences, with an
overall yield of 27% and 25%, respectively. It is worthwhile to menti
on that the introduction of a phenylseleno moiety to the C-2 alpha pos
ition of the lactone 4 can now be performed in a stereocontrolled fash
ion, providing the key intermediate 5 alpha in 75% yield.