The possibility of allyl as the protection group of the hydroxyls in n
ucleosides was studied. Allyl bromide can react with thymidine and ade
nosine in the presence of NaOH to give O-allyl protected nucleosides i
n good yield. PdCl2 can be used as a reagent for the deprotection. It
was found that PdCl2 can selectively deprotect the p-methoxytrityl, di
-p-methoxytrityl or both of the p-methoxytrityl, di-p-methoxytrityl an
d allyl group.