Crystal Structure and Conformation of 8-(2-Hydroxyethylamino) and 8-(Pyrrolidin-1-yl) Adenosines

In the course of investigation of 8-alkylamino substituted adenosines, the title compounds were synthesized as potential partial agonists for adenosine receptors. The structure determination of these compounds was carried out with the X-ray crystallography study. Crystals of 8-(2-hydroxyethylamino)adenosine are monoclinic, space group P 21; a = 7.0422(2), b = 11.2635(3), c = 8.9215(2) A, β = 92.261(1)°, V = 707.10(3) A3, Z = 2; R-factor is 0.0339. The nucleoside is characterized by the anti conformation; the ribose ring has the C(2′)-endo conformation and gauche–gauche form across C(4′)–C(5′) bond. The molecular structure is stabilized by intramolecular hydrogen bond of N–H·O type. Crystals of 8-(pyrrolidin-1-yl)adenosine are monoclinic, space group C 2; a = 19.271(1), b = 7.3572(4), c = 11.0465(7) A, β = 103.254(2)°, V = 1524.4(2) A3, Z = 4; R-factor is 0.0498. In this compound, there is syn conformation of the nucleoside; the ribose has the C(2′)-endo conformation and gauche–gauche form across C(4′)–C(5...