Résumé
The synthesis of the diastereoisomers of nu(2),epsilon,zeta-D-CNA dinucleotide building units of nucleic acids and their (2',5')-nu(2),epsilon',zeta'-D-CNA analogues, in which the epsilon and zeta torsional angles are stereocontrolled by a dioxaphosphormane ring structure (D-CNA family) is described from a common 3-deoxy-3-(hydroxyrnethyl)-D-allofuranose intermediate. NMR spectroscopic and circular dichroism structure analysis of nu(2),epsilon,zeta-D-CNA shows that the sugar puckering is fixed in the C-2'-endo conformation and that these D-CNA structural elements allow stabilization of the epsilon/zeta torsion angle combinations, which are significantly different from the typical combindtions observed in canonical A- or B-form duplexes.