Synthesis, structure and biological activity of 6-r(3)si(ge, sn)-substituted 5-fluorouracils.

Direct lithiation of 1-(2-tetrahydrofuryl)-5-fluorouracil (Ftorafur) has been investigated. The treatment of ftorafur with lithium diisopropylamide (LDA)at -70 in ether-hexane, followed by the reaction with various electrophiles afforded the corresponding 6-substituted silicon, germanium and tin derivatives of ftorafur. The results of biological investigation indicate the ability of germanium-modified nucleoside analogues to interfere with transcription and replication processes.