Analogues of S-adenosylhomocysteine as potential inhibitors of biological transmethylation. Synthesis of analogues with modifications at the 5'-thioether linkage.

The synthesis of S-adenosylhomocysteine analogues, in which the 5'-thioether linkage is replaced by an oxygen or nitrogen isostere, has been investigated. These compounds were disigned to be resistant to enzyme-catalyzed hydrolytic cleavage of the 5'-substituent. The amine analogue Id and two amide analogues 20 were prepared via alkylation or acylation of appropriately blocked adenosine derivatives. These new analogues were evaluated as inhibitors of catechol O-methyltransferase and tRNA methylases and found to have poor inhibitory activity.