Methyl 2-((2Z,5Z)-2-{(E)-2-[1-(4-hydroxyphenyl)ethylidene]hydrazin-1-ylidene}-4-oxo-3-phenyl-1,3-thiazolidin-5-ylidene)acetate

In the title compound, C20H17N3O4S, all non-H atoms, except those of the phenyl ring, are approximately coplanar [maximum deviation = 0.2214 (1) Å], and the dihedral angle between their best plane and the benzene ring is 53.13 (1)°. A short intramolecular O⋯S contact of 2.838 (1) Å is formed between the ester carbonyl O atom and the S atom of the thiazolidine ring. In the crystal, molecules associated via O—H⋯O, C—H⋯O and C—H⋯S hydrogen bonds form layers parallel to (010), with only C—H⋯O-type short contacts between the molecules in adjacent layers.


Comment
Thiazolidinone scaffold compounds have received much attention from organic and medicinal chemists due to their therapeutic diversity coupled with their commercial viability. Recently, 4-thiazolidinones have exhibited many interesting bio-activity profiles such as anti-cancer (Dayam et al., 2006) and anti-mycobacterial agents (Srivastava et al., 2005), COX-1 inhibitors (Look et al. 1996), non-nucleoside inhibitors of HIV- RT (Barreca et al., 2001) and anti-histaminic agents (Diurno et al., 1992). In view of these properties the title compound has been synthesized among a series of other 4-thiazolidinones to investigate the relationship between their crystal structures and their antibacterial activity.
In the title compound ( Fig. 1) Table 1 is between the layers. The interlayer regions are occupied by the N-phenyl and ester groups between which there are no significant interactions.

Experimental
A mixture of 283 mg (1 mmol) (2Z)-2-[1-(4-methylphenyl)ethylidene]-N-phenylhydrazinecarbothioamide and 142 mg (1 mmol) dimethyl but-2-ynedioate in 50 ml of ethanol was refluxed and monitored by TLC until completion of the reaction. The excess solvent was evaporated under vacuum and the solid obtained was recrystallized from ethanol to afford clear yellow plates (M.p. 541-543 K) of X-ray quality.

Refinement
The hydroxyl H atom was found from a difference Fourier map [O4-H4O = 0.84 (2) Å] and refined freely. H atoms bonded to C were placed in geometrically idealized positions and constrained to ride on their parent atoms C-H = 0.95 Å (aromatic H) and 0.98 Å (methyl H), with U iso (H) = 1.5 U iso (C) for methyl H atoms and U iso (H) = 1.2 U iso (C) for other H atoms.

Figure 1
Perspective view of the title molecule with 50% probability displacement ellipsoids.

Special details
Experimental. The diffraction data were collected in three sets of 606 frames (0.3° width in ω) at φ = 0, 120 and 240°. A scan time of 40 sec/frame was used. Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles Refinement. Refinement on F 2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses 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 observed criterion of F 2 > σ(F 2 ) is used only for calculating -R-factor-obs 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.