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Oligonucleotides Containing Pyrazolo[3,4‐ d ]pyrimidines: The Influence of 7‐Substituted 8‐Aza‐7‐deaza‐2′‐deoxyguanosines on the Duplex Structure and Stability
Author(s) -
Seela Frank,
Becher Georg
Publication year - 1999
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/(sici)1522-2675(19991006)82:10<1640::aid-hlca1640>3.0.co;2-n
Subject(s) - chemistry , oligonucleotide , duplex (building) , dna , solid phase synthesis , combinatorial chemistry , stereochemistry , phosphoramidite , oligonucleotide synthesis , nucleic acid , peptide , biochemistry
Oligonucleotides containing 7‐substituted 8‐aza‐7‐deazaguanines (=6‐amino‐1,5‐dihydro‐4 H ‐pyrazolo[3,4‐ d ]pyrimidin‐4‐ones) were prepared by automated solid‐phase synthesis. A series of 7‐alkynylated 8‐aza‐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.