| abstract |
This invention is directed to novel 3,4-disubstituted and 3,4,6-trisubstituted pyrazolo[3,4-d]pyrimidines and to the use of these compounds in the preparation of oligonucleotides. The invention is also directed to nucleosides and mono- and oligonucleotides comprising at least one of these pyrazolopyrimidines, and to the use of the resulting novel oligonucleotides for diagnostic purposes. More particularly, the pyrazolopyrimidines of the present invention are of formula (I), wherein R1 is hydrogen, or a sugar moiety optionally substituted at its 3' or its 5' position with monophosphate, diphosphate, triphosphate, or a reactive group suitable for nucleotide bond formation; provided that when R3 is hydrogen, then R1 cannot be hydrogen; R3 is hydrogen or the group -W-(X)n-A; each of W and X is independently a chemical linker arm; A is an intercalator, an electrophilic crosslinker or a reporter group; each of R4 and R6 is independently H, OH, SR, NH2, or NH(CH2)tNH2; R is H or C1-6alkyl; n is zero or one; and t is zero to twelve. The novel oligo- and polynucleotides are useful in the identification, isolation, localization and/or detection of complementary nucleic acid sequences of interest in cell-free or cellular systems. Therefore, the invention further provides a method for identifying target nucleic acid sequences, which method comprises utilizing an oligo- or polynucleotide probe comprising at least one of a labeled pyrazolo[3,4-d]pyrimidine of the present invention. |