Watson–Crick Base-Pairing Properties of Nucleic Acid Analogues with Stereocontrolled α and β Torsion Angles (α,β-D-CNAs)We thank the Centre Informatique National de l'Enseignement Supérieur (CINES) and the Centre Interuniversitaire de Calcul de Toulouse (CALMIP) for the generous allocation of computer time and Dr. M. Erard for assistance with the CD experiments. D-CNAs=constrained nucleic acids with dioxaphosphorinane ring.