Stereochemistry of nucleic acids and their constituents. XIV. Crystal and molecular structure of 2,4-dithiouridine monohydrate

Crystal structure and conformation of 5-aminouridine

“…This value supports the common relation between the puckering of the ribose and the orientation of the base (Sundaralingam, 1969;Egert, Lindner, Hillen & Gassen, 1977b). From the data listed in Table 4 ( Rahman & Wilson, 1970;Hawkinson, 1977;Lin & Sundaralingam, 1971;Schwalbe & Saenger, 1973;Egert, Lindner, Hillen & Gassen, 1977b) it appears that this relation could be the result of the preferred formation of the intramolecular hydrogen bond C(6)-H...O(5') (Saenger, 1973), which requires a greater dihedral angle X in C(2')-endo than in C(3')-endo puckering. Moreover, the C(5')-O(5') bond is fixed by this interaction gauche to C(3')-C(4') and to O(1')-C(4') with dihedral angles of 50.1 and -69.7 ° (Fig.…”

The crystal structure of dextrorotary 2'-O-tetrahydropyranyluridine

“…C(I') is even further displaced (0.088 A) from the plane. These deviations are of the same order as those found in fl-uridine, deoxyuridine (Rahman & Wilson, 1972) and 2,4-dithiouridine monohydrate (Lin & Sundaralingam, 1971) but are considerably smaller than those found in 5-chlorouridine (Hawkinson & Coulter, 1971), 5-bromouridine (Iball, Morgan & Wilson, 1966) and 4-thiouridine hydrate (Saenger & Scheit, 1970). …”

3,6-Dimethyl-5-thioformylpyrrolo[2,1-b]thiazole

“…The thioformyl sulphur--carbon bond length shows significant shortening from the formal single-bond length. In other resonating molecules the exocyclic carbonsulphur bond lengths are 1-660 (5) and 1.653 (5)A (Lin & Sundaralingam, 1971); 1.657 A (Downie, Harrison, Raper & Hepworth, 1972); 1.650 A (Karle & Karle, 1965) and 1.666 A (Form, Raper & Downie, 1973). These show good agreement with the value 1.656 (2) A for this molecule.…”