Promiscuous Watson−Crick Cross-Pairing within the Family of Pentopyranosyl (4‘→2‘) Oligonucleotides1

formula: see text The D-beta-ribo, D-beta-xylo, L-alpha-lyxo, and L-alpha-arabino members of the pentopyranosyl (4'-->2') oligonucleotide family show efficient intersystem cross-pairing among each other. This family of configurationally isomeric and conformationally well-defined pairing systems offers an opportunity to study structural factors that determine cross-communication between informational oligonucleotide systems of different backbone structure.