New synthesis of functionalized pyrimidine nucleosides

Abstract

Cerium(IV) compound has been utilized extensively for a variety of oxidative transformations. These reactions have been limited to the oxidative coupling reactions. It has been found that silylated pyrimidine bases reacted with 1, 3-dioxolane in the presence of cerium ammonium nitrate to give the corresponding acyclic nucleosides in good yields. Glycals are the key intermediates in the synthesis of C-nucleosides. Glycals reacted with heterocyclic bases mediated by benzeneselenenyl chloride to give 2``-(selenophenyl)-substituted nucleosides. The introduction of seleno-group and base with high stereoselectivity and regioselectivity was performed in good yield. During the study on developing functionalization of uracil derivatives at C-5 position of uracils, we have found that uracil reacted with diphenyldiselenide in the presence of manganese(III) acetate in acetic acid to give 5-phenylselenenyl uracil. Formation of a selenium electrophile which is generated by the reaction of manganese(III) acetate with diphenyldiselenide appears to be involved in this reaction. Nucleosides modified at C-5 position of the pyrimidine base have become important components of synthetic oligonucleosides probes. It has been found that the pyrimidine bases reacted with diethyl malonate in the presence of manganse(III) acetate in acetic acid to afford the pyrimidine bases modified at C-5 by C-C-bond formation. Various pyrimidine bases reacted with diethyl malonate and manganese(III) acetate to give 5-(diethyl acetoxy-methanedicarboxylate) pyrimidines in good yields. (S)-5-(t-Butyl-diphenylsiloxymethyl)-2-(5H)-furanone reacted with 1,3-dioxolane in the presence of $(n-Bu_4N)_2S_2O_8$ to give the 3``-1,3-dioxolanylated lactone by the antiaddition with high stereoselectivity. The 3``-deoxy-3``-branched chain-substituted sugar derivatives can be used for coupling with silylated base with various Lewis acid. 3``-Masked formylated nucleoside will serve as valuable synthetic intermediates...