Hydrogermylation of 5-ethynyluracil nucleosides: formation of 5-(2-germylvinyl)uracil and 5-(2-germylacetyl)uracil nucleosides

A stereoselective radical-mediated hydrogermylation of the protected 5-ethynyluracil nucleosides with trialkyl-, triaryl,- or tris(trimethylsilyl)germanes gave (Z)-5-(2-germylvinyl)uridine, 2'-deoxyuridine, or ara-uridine as major products. Reaction of the β-triphenylgermyl vinyl radical intermediate with oxygen and fragmentation of the resulting peroxyradical provided also 5-[2-(triphenylgermyl)acetyl]pyrimidine nucleosides in low to moderate yields. Thermal isomerization of the latter in MeOH occurred via a four-centered activated complex, and subsequent hydrolysis of the resulting O-germyl substituted enol yielded 5-acetyluracil nucleosides in quantitative yield.

Synthesis of 5-radioiodoarabinosyl uridine analog for probing HSV-1 thymidine kinase gene: an unexpected chelating effect

Tumor cells transduced with herpes simplex virus thymidine kinase gene has been intensively applied to the field of positron emission tomography via imaging of its substrate. As a pilot synthesis approach, a facial preparation of 5-[125I]iodoarabinosyl uridine starting from commercial available uridine is reported herein. Interestingly, the tin group in 5-trimethylstannyl arabinosyluridine was easily removed during purification. The destannylation through the formation of a six-ligand coordination involving 2'-hydroxyl and tin was thereby proposed.