Received 12 September 2013
There are two independent molecules in the asymmetric unit of the title compound, C13H13NO5S, in both of which the ester substituent is nearly coplanar [C-C-C-O torsion angles = 2.7 (7) and -0.8 (7)°] with the planar fragment of the bicycle due to the formation of a strong O-HO intramolecular hydrogen bond. The vinyl group at the ring N atom is approximately orthogonal to the heterocyclic mean plane [C-N-C-C torsion angles = 103.1 (6) and 98.2 (5)°]. The refinement was performed on a two-component, non-merohedrally twinned crystal [population ratio = 0.483 (3):0.517 (3).
Data collection: CrysAlis CCD (Agilent, 2011); cell refinement: CrysAlis CCD; data reduction: CrysAlis RED (Agilent, 2011); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: XP in SHELXTL; software used to prepare material for publication: SHELXTL.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: BG2518 ).
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