The DNA-stabilising nucleoside 7-iodo-2′-deoxytubercidin: its structure in the solid state and in solution

Abstract

The crystal structure of 7-iodo-2′-deoxytubercidin 2 has been determined and was compared with those of 2′-deoxytubercidin 3 and 2′-deoxyadenosine 4. The bulky 7-iodo substituent lies 13.2 pm below and the nitrogen of the 6-amino group 5.5 pm above the 7-deazapurine plane. The puckering of compound 2 is _3′E while compound 3 shows a ^2′T_3′ sugar pucker. The conformation in aqueous solution, determined by ¹H NMR spectroscopy, is only slightly different, showing a ^2′E conformation. The glycosylic bond torsion angle is anti in all cases.