Nucleosides and Nucleotides. XIV. Synthesis of 6-Alkylthiouridines and Uridine-6-sulfonic Acid

Abstract

Treatment of 5'-O-acetyl-2', 3'-O-isopropylidene-5-bromouridine with benzyl mercaptan yielded both 5-benzylthio and 6-benzylthio derivatives, (IIa) and (IIIa). Deprotection of those derivatives gave 5-benzylthiouridine (IIc) and 6-benzylthiouridine (IIIc). Treatment of IIIa with methoxide followed by H₂S afforded 2', 3'-O-isopropylidene-6-thiouridine (IV). Methylation of IV gave 6-methylthiouridine (VI) after deblocking. Oxidation of IV with hydrogen peroxide afforded uridine-6-sulfonic acid (VII), an orotidine analog. Nuclear magnetic resonance and circular dichroism data were given and conformations of these nucleosides were discussed.