Diastereoselective Synthesis of Conformationally Restricted Dinucleotides Featuring Canonical and Noncanonical α/β Torsion Angle Combinations(α,β-D-CNA)

The synthesis of the four possible diastereoisomers of α,β‐D‐CNA 5′‐XT (X = A, T, G and C) building units of nucleic acids, in which the α and β torsional angles are stereocontrolled by a dioxaphosphorinane ring structure (D‐CNA family) is described. The crystal structure analysis of the (RC5′,SP)‐configured α,β‐D‐CNA TT dimer demonstrates that the α and β torsional angles are restricted to the canonical {gauche(–),trans} conformation typically observed in DNA duplexes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)