Oligonucleotides Containing Pyrazolo[3,4-d]pyrimidines: The Influence of 7-Substituted 8-Aza-7-deaza-2′-deoxyguanosines on the Duplex Structure and Stability

✍ Scribed by Frank Seela; Georg Becher

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: German
• Weight: 186 KB
• Volume: 82
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/(sici)1522-2675(19991006)82:10<1640::aid-hlca1640>3.0.co;2-n

✦ Synopsis

Oligonucleotides containing 7-substituted 8-aza-7-deazaguanines ( 6-amino-1,5-dihydro-4H-pyrazolo[3,4-d]pyrimidin-4-ones) were prepared by automated solid-phase synthesis. A series of 7-alkynylated 8aza-7-deaza-2'-deoxyguanosines (see 4a ± d) were synthesized with the 7-iodonucleoside 3c as starting material and by the Pd 0 /Cu I -catalyzed cross-coupling reaction with various alkynes. Phosphoramidites were prepared from the 7-substituted 8-aza-7-deaza-2'-deoxyguanosine derivatives carrying halogeno, cyano, and hexynyl substituents. From the melting profiles of oligonucleotide duplexes, the T m values as well as the thermodynamic data were determined. A significant duplex stabilization by the 7-substituents was observed for the DNA ´DNA duplexes, but not in the case of DNA ´RNA hybrids.