2-[N-(4-Methoxyphenyl)acetamido]-1,3-thiazol-4-yl acetate

The structural analysis of the title compound, C14H14N2O4S, particularly the presence of an acetyl group at the exocyclic N atom and the C(H)—C(O2CMe)—N acetoxy group in the thiazole ring, may indicate that one of the starting materials, i.e. 2-(4-methoxyanilino)-1,3-thiazol-4(5H)-one, exists in the reaction mixture, at least partially, as a tautomer with an exocyclic amine N atom and an enol group. The acetoxy and acetyl groups deviate from the thiazole plane by 69.17 (6) and 7.25 (19)°, respectively. The thiazole and benzene rings form a dihedral angle of 73.50 (4)°. In the crystal, centrosymmetrically related molecules are connected into dimeric aggregates via C—H⋯O interactions.

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: TK5195).
Dictated by these observations, the aim of the presented work was synthesis of the compound (I) as starting substance for further design of new biologically active compounds.
The C4 acetoxy group and N6 acetyl functionality are oriented differently in relation to the planar thiazole ring. The first one forms a dihedral angle of 79.22 (5)° with the mean plane of this ring whereas the second one is tilted only slightly [dihedral angle: 7.25 (19)°] (Fig. 1).
In the crystal structure, the molecules of (I) are connected by the C5-H5···O21 i hydrogen bonds into centrosymmetric dimers ( Experimental 2-(4-Methoxyanilino)thiazol-4-one in the medium of acetic anhydride was refluxed for 2 h. The obtained solution was evaporated in vacuum and the residue was recrystallized twice from benzene-hexane (1:1) mixtures.

Refinement
All H atoms were located into the idealized positions and were refined within the riding model approximation: C methyl -H = 0.96 Å, C(sp 2 )-H = 0.93 Å; U iso (H) = 1.2U eq (C) or 1.5U eq (C) for methyl H. The methyl groups were refined as rigid groups which were allowed to rotate.

Figure 1
The molecular structure of (I) together with the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level and H atoms are shown as spheres of arbitrary radii.  The hydrogen bonding (dotted lines) in the title structure. Symmetry code: (i) -x,1 -y,1 -z. H atoms not involved in hydrogen bonds have been omitted for clarity. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.37 e Å −3 Δρ min = −0.27 e Å −3 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 > σ(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.