(Z)-2-[Methoxy(phenyl)methylidene]-3,4,5-trimethyl-2,3-dihydro-1,3-thiazole

In the title compound, C14H17NOS, the plane defined by the bridging methylene C atom and its three substituents makes dihedral angles of 14.37 (8)° with the heterocycle and 26.17 (8)° with the phenyl ring, while the dihedral angle between the heterocycle and the phenyl ring is 36.29 (7)°. In the crystal, molecules are linked by C—H⋯π contacts.

In the title compound, C 14 H 17 NOS, the plane defined by the bridging methylene C atom and its three substituents makes dihedral angles of 14.37 (8) with the heterocycle and 26.17 (8) with the phenyl ring, while the dihedral angle between the heterocycle and the phenyl ring is 36.29 (7) . In the crystal, molecules are linked by C-HÁ Á Á contacts.   Table 1 Hydrogen-bond geometry (Å , ).

Related literature
Cg1 is the centroid of the C5-C10 ring.  The molecular structure of the title compound is shown in Fig. 1. The exocyclic double bond has a length of 1.349 (2) Å which is comparable to that observed for a related structure [1.353 Å;Reisser et al., 2003]. The endocyclic double bond length is 1.330 (2) Å [1.332 Å; Reisser et al., 2003]. The angle sum around the methylene carbon atom, C4, amounts to 360° resulting in a trigonal planar environment of the methylene atom. However, this mean plane (C4/O1/C3/C5) is not coplanar with either the plane of the heterocycle (S1/N1/C1-C3) or the plane of the phenyl ring (C5-C10). The corresponding dihedral angles are 14.37 (8)° and 26.17 (8)°, respectively. The dihedral angle between the heterocycle and the phenyl ring is 36.29 (7)°.

Experimental
A solution of 2-(methoxy(phenyl)methyl)-3,4,5-trimethylthiazolium trifluoromethanesulfonate (397 mg, 1.00 mmol) in THF (6 ml) was added dropwise to a stirred suspension of NaH (36 mg, 1.5 mmol) in dry THF (5 ml) at -20 °C under nitrogen, and the reaction mixture was allowed to stir for 36 h in the dark. After warming to room temperature, the solvent was removed under vacuum, and the residue was suspended in dry toluene (20 ml) and filtered through a celite pad under nitrogen. Then the solvent was evaporated to give 205 mg (0.829 mmol, 83%) of the title compound as 2:1 mixture of Z:E isomers. Crystals of the title compound suitable for X-ray diffraction analysis were grown by slow evaporation of a solution in n-pentane under nitrogen.

Refinement
The C-bound H atoms were included in calculated positions and treated as riding atoms: C-H = 0.95 and 0.98 Å for CH and CH 3 -atoms, respectively, with U iso (H) = k × U eq (C), where k = 1.5 for CH 3 H atoms and = 1.2 for other H atoms. The methyl groups were allowed to rotate along the C-X bonds (X = C, O, N) to best fit the experimental electron density.  The molecular structure of the title molecule, with atom labelling. Displacement ellipsoids are drawn at 50% probability level.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 > 2σ(F 2 ) is used only for calculating R-factors(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.