Triple‐Helix Formation of Oligodeoxynucleotides Containing [(3′S,5′R)‐2′‐Deoxy‐3′,5′‐ethano‐β‐D‐ribofuranosyl]nucleosides (“Bicyclo‐deoxynucleosides”)

An enhanced preference for complexing to an RNA complement on the Hoogsteen side of the nucleobase is the consequence of the sugar modification in oligonucleotides of bicyclodeoxyguanosine 3. Furthermore, oligonucleotides containing bicyclothymidine 1 and bicyclodeoxycytidine 2 provide evidence of specific differences in the preferred sugar conformation of the nucleosides in the third strand in DNA triple helices.