A practical synthesis of 4′-thioribonucleosides

Stereoselective synthesis of 4′-selenonucleosides using the Pummerer glycosylation reaction

“…15 By analogy with these methods, we propose the use of a 2,3-O-isopropylidene-protected 1,4-anhydro-4-seleno-D D-ribitol derivative (compound a, Scheme 2). Oxidation to selenoxide (b) and Pummerer glycosylation with silylated pyrimidine or purine bases, as developed by Matsuda's group 16 for the synthesis of 4 0 -thio nucleosides should lead to the desired nucleoside derivatives (c) with good selectivity for the desired bisomers.…”

Synthesis of 4′-Thionucleosides as Antitumor and Antiviral Agents

“…To prove the usefulness of the latter Pummerer-type glycosylation, we applied it to the synthesis of 4′-thioribonucleosides. 45) We then further extended our study to the synthesis of purine 4′-thioribonucleosides and found that some of the purine 4′-thioribonucleoside derivatives exhibited anti-angiogenesis activity based on our primary screening system. 46) To obtain several purine analogues, including 4′-thioguanosine, we modified the original synthesis of 4′-thioguanosine.…”

Organocatalytic Asymmetric Synthesis of Spiro‐Tetrahydrothiophene Oxindoles Bearing Four Contiguous Stereocenters by One‐Pot Michael–Henry‐Cascade–Rearrangement Reactions

“…However,c urrent asymmetric synthetic methods only led to the assembly of functionalized tetrahydrothiophenes with three consecutive stereogenic centers. Simultaneously constructing tetrahydrothiophenes with four contiguous stereocenters remains af ormidable challenge.Owing to the synthetic challenge and therapeuticv alue, it is highly desirable to develop novel synthetica pproaches to assemble highly functionalized chiral spiro-tetrahydrothiophene oxindole scaffolds bearing four contiguous stereocenters.[7] Previously,T akahata et al reported ap ractical synthesis of 4'-thioribonucleosides startingf rom 5-thioarabinose through the sulfonium-mediated ring-contraction reaction.[8] Inspired by this work, [8] and our previous findings on asymmetric synthesis of organosulfur scaffolds [9] ,h erein, novel Michael-Henry-cascaderearrangement reactions were designed to address the abovementioned bottleneck. We envisioned that the highly functionalized spiro-tetrahydrothiophene oxindole scaffold with four consecutive stereogenic centers couldb ee fficiently constructed via the sulfonium-mediated rearrangementr eaction [8,10] of the spiro-tetrahydrothiopyran oxindole scaffold (Scheme 1).…”

“…[8] Inspired by this work, [8] and our previous findings on asymmetric synthesis of organosulfur scaffolds [9] ,h erein, novel Michael-Henry-cascaderearrangement reactions were designed to address the abovementioned bottleneck. We envisioned that the highly functionalized spiro-tetrahydrothiophene oxindole scaffold with four consecutive stereogenic centers couldb ee fficiently constructed via the sulfonium-mediated rearrangementr eaction [8,10] of the spiro-tetrahydrothiopyran oxindole scaffold (Scheme 1).…”

“…We envisioned that the highly functionalized spiro-tetrahydrothiophene oxindole scaffold with four consecutive stereogenic centers couldb ee fficiently constructed via the sulfonium-mediated rearrangementr eaction [8,10] of the spiro-tetrahydrothiopyran oxindole scaffold (Scheme 1). This scaffold could be efficiently constructed using the organocatalytic asymmetricM ichael-Henry [11] cascade process.…”