51375-22-5

Treatment of 4-thiouridine with phenacyl bromide, bromoacetone, and ethyl bromoacetate gave the corresponding 4-thioalkylcarbonyl derivatives.The sulfur extrusion reactions of these compounds afforded ribosides of 4-phenylacylidene-2(3H)-pyrimidone, 4-acetonylidene-2(3H)-pyrimidone, and 2-pyrimidone-4-acetic ester, respectively.The ease of sulfur extrusion depends on the electron-withdrawing ability of the carbonyl group attached to the 4-S-methylene group.Sulfur extrusion reactions starting from 6-thioinosine similarly gave the ribofuranosides of 6-phenacylpurine and 6-acetopurine.These purine ribosides exist mainly as the enol form rather than the keto form.Keywords- sulfur extrusion reaction; thionucleosides; nucleosides; triphenylphosphine; UV; NMR