Résumé
The synthesis of diastereoisomers of spiro xylo-epsilon,zeta-D-CNA dinucleotide building units of nucleic acids, in which the epsilon and zeta torsional angles are stereocontrolled by a dioxaphosphorinane ring structure (D-CNA family), is described from uridine with a Mukaiyama's aldol condensation as key reaction. The NMR structure analysis showed that delta, epsilon and zeta torsional angles of the (S-C3', R-P)- and (S-C3', S-P)-configured xylo-epsilon,zeta-D-CNATT dimer are restricted to the {delta, epsilon, zeta} {cis, trans, gauche(+)} or {cis, trans, gauche(-)} conformation, respectively, that are significantly different from those typically observed in A- or B- type duplexes. (C) 2007 Elsevier Ltd. All rights reserved.