Nucleosides with furanyl scaffolds

Energy, orbital and structural stacking landscape of a purine homodimer system

The multidimensional study, combining the extensive calculations of potential energy surfaces for the parallel-displaced configurations and methods such as energy decomposition and natural bond orbital analysis, has been carried out. The resulted data give an energy, orbital and structural landscapes of this biologically essential system. The balance of the two energy sources, electrostatic and dispersion, is clearly visible. The obtained results, taken as a whole, provide an insight into the hierarchy of intermolecular interactions in the purine system, together with their sources.

Nucleosides with Transposed Base or 4'-Hydroxymethyl Moieties and Their Corresponding Oligonucleotides

This review focuses on 4'-hydroxymethyl- or nucleobase-transposed nucleosides, nucleotides, and nucleoside phosphonates, their stereoisomers, and their close analogues. The biological activities of all known 4'-hydroxymethyl- or nucleobase-transposed nucleosides, nucleotides, and nucleoside phosphonates as potential antiviral or anticancer agents are compiled. The routes that have been taken for the chemical synthesis of such nucleoside derivatives are described, with special attention to the innovative strategies. The enzymatic synthesis, base-pairing properties, structure, and stability of oligonucleotides containing nucleobase- or 4'-hydroxymethyl-transposed nucleotides are discussed. The use of oligonucleotides containing nucleobase- or 4'-hydroxymethyl-transposed nucleotides as small oligonucleotide (e.g., human immunodeficiency virus integrase) inhibitors, in applications such as antisense therapy, silencing RNA (siRNA), or aptamer selections, is detailed.

Reduction of 4-(Haloalkyl)azetidin-2-ones with LiAlH4 as a Powerful Method for the Synthesis of Stereodefined Aziridines and Azetidines

[reaction: see text] A new synthesis of stereodefined aziridines and azetidines, starting from 4-(1- or 2-haloalkyl)azetidin-2-ones, is described. Treatment of the latter compounds with LiAlH(4) gave 1,2-fission of the beta-lactam, followed by an intramolecular nucleophilic substitution of the halogen, giving rise to the formation of 2-(1-alkoxy-2-hydroxyethyl)aziridines in the case of 4-(1-haloalkyl)azetidin-2-ones and of 2-(1-alkoxy-2-hydroxyethyl)azetidines in the case of 4-(2-haloalkyl)azetidin-2-ones. The resulting 2-(1-alkoxy-2-hydroxyethyl)aziridines were transformed into the corresponding trans-3,4-substituted oxolanes via an intramolecular nucleophilic ring opening, triggered by AlCl(3).