Cover Picture: Chem. Eur. J. 23/2002

✍ Scribed by Dae-Ro Ahn; Anita Egger; Christian Lehmann; Stefan Pitsch; Christian J. Leumann

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: English
• Weight: 20 KB
• Volume: 8
• Category: Article
• ISSN: 0947-6539
• DOI: 10.1002/1521-3765(20021202)8:23<5275::aid-chem5275>3.0.co;2-z

✦ Synopsis

The cover picture shows the mirror-image CD spectral relationship rationalized by building molecular models of right-and left-handed nucleic acid duplex structures. In the remarkable bicyclo[3.2.1]amide±DNA constitution, a conformational switch of the amide relais group linking the backbone and nucleobase allows right-as well as lefthanded helical base pairing, depending on the complementary duplex strand. The respective conformations are related to antipodal carbonyl interlocking between the rigid bicyclic unit, assisted by interresidual axially chiral intrastrand hydrogen bonding through the amide functional groups. A right-handed helix is maintained for the heteroduplex with oligonucleotides of natural chirality, whereas the mirror-image lefthanded spectrum is observed for pairing with enantiomeric RNA as well as with the duplex uniquely composed of bicyclo[3.2.1]amide nucleotides. This is discussed in more detail by C. J. Leumann et al. on p. 5312 ff. (Illustration provided by C.