Nucleic Acids Research, 1983, Vol. 11, No. 22 7999-8005
© 1983
CHEMISTRY |
Crystal and molecular structure of (E)-5-(2-bromoviayl-2'-deoxyuridine)
Central Research Institute for Chemistry, Hungarian Academy of Sciences Budapest-114, POB 17, H-1525, Hungary
*To whom correspondence should be addressed.
Revised October 26, 1983. Accepted October 26, 1983.
(E)-5-(2-bromovinyl-2'-deoxyuridine) crystallizes in the space group P21, with a = 12.976(1), b = 4.800(1), c = 20.385(2) Å, ß = 96.88(1)°, Z = 4 (two molecules a ancT b in the asymmetric unit). The structure has been determined by the use of 2400 diffractometer reflexions and refined by leastsquares to R of 0.053. Conformational features of both molecules a and b resemble those of thymidine. The ribofuranose rings assume the rare C(3')exo form observed also in thymidine. Similarly, the torsion angles around the glycosidic bonds (x % 40(1) and 56(1)0 fall in the anti range. In each molecule the best plane of the 2-bromovinyl moiety is bent out of the leastsquares plane of the pyrimidine base by 6°, so that the positively charged C(8)–H(8) group can donate an intramolecular hydrogen bond to 0(4) atom. Eight strong and weak intermolecular hydrogen bridges are built up between the symmetry independent and related molecules forming a complicated three dimensional hydrogen bond network.