A novel route to a chiral building block for the preparation of cyclopentenyl carbocyclic nucleosides. Synthesis and anticancer activity of enantiomeric neplanocins A

A novel route to both enantiomers of a cyclopentene building block was developed and applied to the synthesis of enantiomeric neplanocins A.

New Carbocyclic Nucleosides with a Constrained Bicyclo[2.2.1]Heptane Fragment as a Glycoside Moiety

Nucleosides with a norbornane fragment as sugar moiety (Figure 1) were found to have antiviral and anticancer activity [1]. [...]

Investigation of 5’-Norcarbocyclic Nucleoside Analogues as Antiprotozoal and Antibacterial Agents

Carbocyclic nucleosides have long played a role in antiviral, antiparasitic, and antibacterial therapies. Recent results from our laboratories from two structurally related scaffolds have shown promising activity against both Mycobacterium tuberculosis and several parasitic strains. As a result, a small structure activity relationship study was designed to further probe their activity and potential. Their synthesis and the results of the subsequent biological activity are reported herein.

Synthesis of Carbocyclic Nucleosides (+)-Neplanocin A, (+)-Aristeromycin and 4'-epi-(+)-Aristeromycin from D-Fructose

D-Fructose is used as the chiral pool starting material for the stereoselective total synthesis of (+)-neplanocin A. Zinc mediated fragmentation, ring-closing metathesis and oxidative rearrangement of cyclic tertiary allylic alcohol are used as the key steps in achieving the synthesis of key carbocylic intermediate. Further, stereoselective total synthesis of 4'-epi-(+)-aristeromycin and the conversion of (+)-neplanocin A to a mixture of (+)-aristeromycin and 4'-epi-(+)-aristeromycin are described.

Glycosylation reactions mediated by hypervalent iodine: application to the synthesis of nucleosides and carbohydrates

To synthesize nucleoside and oligosaccharide derivatives, we often use a glycosylation reaction to form a glycoside bond. Coupling reactions between a nucleobase and a sugar donor in the former case, and the reaction between an acceptor and a sugar donor of in the latter are carried out in the presence of an appropriate activator. As an activator of the glycosylation, a combination of a Lewis acid catalyst and a hypervalent iodine was developed for synthesizing 4’-thionucleosides, which could be applied for the synthesis of 4’-selenonucleosides as well. The extension of hypervalent iodine-mediated glycosylation allowed us to couple a nucleobase with cyclic allylsilanes and glycal derivatives to yield carbocyclic nucleosides and 2’,3’-unsaturated nucleosides, respectively. In addition, the combination of hypervalent iodine and Lewis acid could be used for the glycosylation of glycals and thioglycosides to produce disaccharides. In this paper, we review the use of hypervalent iodine-mediated glycosylation reactions for the synthesis of nucleosides and oligosaccharide derivatives.