Acta Crystallographica Section E Structure Reports Online (Impact Factor: 0.35). 01/2010; 66(Pt 12):o3217-8. DOI:10.1107/S1600536810046921
Source: PubMed

ABSTRACT The title compound, C(19)H(30)O(9), was prepared by substitution at the C6 position in 1,2;3,4-di-O-isopropyl-idene-6-O-trifluoro-methane-sulfonyl-d-galactose using sodium eth-oxy-malonate in dimethyl-formamide. The conformation is skew-boat (0)S(2), slightly distorted towards boat B(2,5). The inflexible pyran-ose structure makes the title compound a suitable inter-mediate for further synthetic work by keeping stereogenic carbon atoms safe from inversion. Several short intra-molecular C-H⋯ O contacts may stabilize the conformation of the mol-ecule. Inter-molecular C-H⋯O inter-actions also occur.

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    ABSTRACT: Automated structure validation was introduced in chemical crystallography about 12 years ago as a tool to assist practitioners with the exponential growth in crystal structure analyses. Validation has since evolved into an easy-to-use checkCIF/PLATON web-based IUCr service. The result of a crystal structure determination has to be supplied as a CIF-formatted computer-readable file. The checking software tests the data in the CIF for completeness, quality and consistency. In addition, the reported structure is checked for incomplete analysis, errors in the analysis and relevant issues to be verified. A validation report is generated in the form of a list of ALERTS on the issues to be corrected, checked or commented on. Structure validation has largely eliminated obvious problems with structure reports published in IUCr journals, such as refinement in a space group of too low symmetry. This paper reports on the current status of structure validation and possible future extensions.
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    ABSTRACT: The structures of the title compounds (2b and 3) have been investigated in the solid state by X-ray methods. The crystals of 2b are monoclinic, space group P2(1), and of 3 orthorhombic, space group P2(1)2(1)2(1). The cell dimensions are: for 2b, a = 9.910(2), b = 11.745(1), c = 11.810(3) A, beta = 97.32(1) degrees; and for 3, a = 6.103(1), b = 15.954(1), c = 28.855(3) A. Both structures were solved by direct methods, and refined by a full-matrix, least-squares procedure giving for 2b, R = 0.0541 (unit weight), and for 3, R = 0.0451 (RW = 0.0445). The galactopyranose rings of 2b and 3 adopted a twist and a mixed twist-screw conformation, respectively. The absolute configuration at C-7 in 2b, as well as at C-6 in 3, was determined to be (R). Relatively strong intermolecular hydrogen bonds were observed in the crystal structure of 3.
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