Methyl (Z)-3-({5-[(E)-(tert-butylamino)methylidene]-4-oxo-4,5-dihydro-1,3-thiazol-2-yl}sulfanyl)prop-2-enoate

In the title compound, C12H16N2O3S2, the S-vinyl, and tert-butylenamine fragments make dihedral angles of 14.19 (2) and 0.85 (2)°, respectively, with the thiazole ring. In the crystal, molecules are linked into chains with graph-set motifs C(5) along [100] by C—H⋯O interactions. The molecular conformation is stabilized by an intramolecular N—H⋯O hydrogen bond.

The molecular conformation is stabilized by two intramolecular N-H···O and C-H···O hydrogen bonds. Z-configuration was assigned to the geometry of S-vinyl system on the basis of torsion angle of -1.86 (4)° between atom S 2 and methoxy carbonyl group.

Experimental
To a magnetically stirred solution of rhodanine (0.27 g, 2 mmol) and methyl acetylenecarboxylate (0.17 g, 2 mmol) in 10 ml CH~2~Cl~2~, was added dropwise over 10 min, tert-butyl isocyanide (0.45 g, 2 mmol) in 2 ml CH 2 Cl 2 . The mixture was then refluxed for 24 h. The solvent was removed under pressure and the residue was purified by silica gel (Merck 230-400 mesh) column chromatography using n-hexane-diethyl ether (2:3) as eluent. Three products were isolated. The single crystals of the title compound were obtained from the n-hexane-ethyl acetate solution. Orange powder, yield 20%.

Refinement
The hydrogen atom of NH group was found in difference Fourier synthesis. The H(C) atom positions were calculated. All hydrogen atoms were refined in isotropic approximation in riding model with with the Uiso(H) parameters equal to 1.2 supplementary materials sup-2 Ueq(Ci), for methyl groups equal to 1.5 Ueq(Cii), where U(Ci) and U(Cii) are respectively the equivalent thermal parameters of the carbon atoms to which corresponding H atoms are bonded.

Figures
Fig . 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids and the atomic numbering. The dashed lines show N-H··· O intramolecular interaction.

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.
Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.