The invention relates to a compound of formula (I), wherein R.sup.1 is
NR.sup.3 R.sup.4, OR.sup.3 or SR.sup.3 with R.sup.3 and R.sup.4 being H or
C.sub.n H.sub.2n+1 independently of each other and being the same or
different, n being a whole number from 1 to 12; R.sup.2 is equal to
C.sub.m H.sub.2m --C(X)--Y with X being .dbd.O, .dbd.S or .dbd.N, Y being
equal to OR.sup.3, NR.sup.3 R.sup.4 or SR.sup.3, R.sup.3 and R.sup.4
having the same meaning given above, and m being a whole number from 1 to
4; or R.sup.2 is equal to C.sub.m H.sub.2m --Z--Y' with Z being a
sulfonyl, phosphonyl, ether or amine group, Y' being equal to H, C.sub.n
H.sub.2n+1, OR.sup.3, NR.sup.3 R.sup.4 or SR.sup.3 then Z is sulphonyl or
phosphonyl group, n, R.sup.3 and R.sup.4 having the meaning given above,
and Y' being equal to C.sub.n H.sub.2n+1 when Z is an ether or an amine
group; A, B, and D are the same or different and mean CR.sup.5 R.sup.6, O,
NR.sup.7 ou S independently of each other with R.sup.5, R.sup.6 and
R.sup.7 being H or C.sub.n H.sub.2n+1, independently of each other, n
having the meaning given above; and C is equal to CR.sup.8 or N with
R.sup.8 having the meaning of R.sup.5 independently, A--B, B--C or C--D
not being two identical heteroatoms; and nucleobase means thymine,
uracile, adenine, cytosine, guanine, isocytosine, isoguanine, xanthine or
hypoxanthine. The invention also relates to a method for producing these
derivatives and to their use in pairing and/or testing systems.
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