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Chemistry of the phenoxathiins and isosterically related heterocycles. XXX . The crystal and molecular structure of 2‐AZA‐phenoxathiin 2‐oxide: Further evidence in support of the relationship between the 13 C‐NMR chemical shift of C‐10a resonance and the molecular dihedral angle
Author(s) -
Caldwell S. R.,
Turley J. C.,
Martin G. E.,
Dwiggins C. A.,
Hossain M. B.,
Mendenhall J. V.,
Van Der Helm D.
Publication year - 1984
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570210237
Subject(s) - chemistry , monoclinic crystal system , diffractometer , crystallography , crystal structure , oxide , diffraction , stereochemistry , organic chemistry , physics , optics
The synthesis of 2‐azaphenoxathiin 2‐oxide ( 4 ) and the total assignment of the 13 C‐nmr spectrum is described. Facile assignment was obtained from the assigned spectrum of 2‐azaphenoxathiin with additivities obtained from a comparison of 1‐azaphenoxathiin and its N ‐oxide. The crystal structure has also been determined from three dimensional X‐ray diffraction data. The compound crystallizes in the monoclinic space group P2 1 /n with a = 17.50(2)Å, b = 7.147(3)Å, c = 16.044(7)Å, β = 110.60(5) and Z = 8. Intensity data were collected at ‐ 135 ± 2°C on an automatic diffractometer using nickel‐filtered CuKα radiation. The structure was solved by direct methods and was refined by least‐squares techniques to give a final R‐value of 0.045 for all 3831 independent reflections.