CRYSTAL STRUCTURE OF N-ACETYL DERIVATIVES OF TWO SUGAR AMINO NITRILES
Vratislav Langer 1, Dalma Gyepesová 2, Lubomír Smrcok 2, Bohumil Steiner3, Miroslav Koóš 3
1Department of Inorganic Chemistry,
Chalmers University of Technology and University of
Goteborg, S-41296 Gothenburg, Sweden
2Institute of Inorganic Chemistry, Slovak
Academy of Sciences, SK-842 36 Bratislava,Slovak Republic,
uachgyep@savba.sk
3Institute of Chemistry, Slovak Academy of
Sciences, SK-842 38 Bratislava Slovak Republic
The compounds, methyl 4-acetamido-4-cyano-4,6-dideoxy-2,3-O-isopropylidene- a-L-talopyranoside (I) and methyl 4-acetamido-4-cyano-4,6-dideoxy-2,3-O-isopropy-lidene-b-D-allopyranoside (II) were obtained during investigation on the Strecker-type reactions with sugar 4-uloses.
The crystal structures of these two compounds have been
determined by X-ray diffraction. The unambiguous establishing of
the configuration, which can be detected only from X-ray
structural analysis, confirmed b-L-talo configuration of I and b -D- allo configuration
of II.
I: C13 H20N2O5
is monoclinic, space group P21 with a = 8.7357(2),
b = 8.5982(2), c = 9.95500(10) A, a=
104.0671(14), Z = 2, Dx, = 1.302 Mg/cm3,
R = 0.0236
II: C13H20N2O5 is hexagonal, space group P62 with a = b = 15.6124(6), c = 10.6318(6) A, Z = 6, Dx = 1.262 Mg/cm3, R = 0.0490
Crystal structures were solved by direct methods and refined by a full-matrix least-squares technique. The crystallographic computations were performed with SHELX86 and SHELX93. The ZORTEP and Siemens XP programs were used for the illustration.
The X-ray data suggest for I a 1C4 conformation which is distorted into the direction of 5E, thus indicating a considerable flattening at C-2. For II X-ray data confirmed b - D-allo configuration and suggests a distorted 4C1 conformation of the pyranose ring.