Synthesis and Structure of Dinucleotides Featuring Canonical and Non‐canonical A‐Type Duplex α, β and δ Torsion Angle Combinations (LNA/α,β‐D‐CNA)

The synthesis of diastereoisomers of LNA/α,β‐D‐CNA dinucleotide building units of nucleic acids in which one δ torsional angle is constrained by an LNA structure and the α and β torsional angles are stereocontrolled by a dioxaphosphorinane ring structure (D‐CNA family) is described. NMR structural analysis showed that the δ a , α b and β b torsional angles of the ( R C5′ , R P )‐configured LNA/α,β‐D‐CNA TT dimer are restricted to the canonical {δ a ,α b ,β b } = { gauche (+)/ anticlinal (+), gauche (–), trans } conformation typically observed in A‐type duplexes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)