5-[(1,3-Dimethyl-5-oxo-2-sulfanylideneimidazolidin-4-ylidene)amino]-2-methylisoindoline-1,3-dione

The title pthalamide-substituted thiohydantoin arose from an unexpected reaction in a deep eutectic dimethylthiourea–tartaric acid solvent system.

The 1 H NMR spectrum confirmed the absence of two H atoms (CH-NH grouping) and the 13 C spectrum showed the downfield shift for the carbon atom of the C-N bond. To establish its structure unambiguously, the crystal structure was determined, which confirmed the presence of the C10 N3 double bond [1.252 (4) Å ] (Fig. 1). The remaining geometrical parameters are comparable with those of a 5-aniline-substituted thiohydantoin reported by our group (Kotha et al., 2019;Cambridge Structural Database refcode FOWGOQ).
The molecular structure of 1 has an angular shape and the mean planes defined by the C10-C12/N1/N2 imidazole ring and C1-C9/N4 pthalimide ring system subtend a dihedral angle of 73.84 (17) . The bond angle of the C8-N3-C10 linker , which connects the thiohydantoin ring with the N-phenyl substituent is 120.6 (3) , some 4 less than the corresponding angle in FOWGOQ (Fig. 2).

data reports
The N1 and N2 nitrogen atoms in the imidazole ring are protected by methyl groups, which rules out the possibility of classical hydrogen bonding in the packing (Fig. 2), but several weak C-HÁ Á ÁO links occur (Table 1).

Synthesis and crystallization
Initially, a deep eutectic mixture was obtained by mixing dimethylthiourea and l-tartaric acid (DMTU:L-(+)TA) in 70:30 ratio at 80 C. After obtaining the melt, aniline 2 (100 mg, 0.57 mmol) and ethylglyoxalate 3 (0.12 ml, 1.14 mmol) were added and the mixture was stirred at the same temperature for 6 h. After completion of the reaction (TLC monitoring), the product was concentrated and purified by silica-gel column chromatography using petroleum ether and ethyl acetate as the eluent to afford the title compound 1 (Fig. 3). Yellow plates were recrystallized from chloroform solution (Kotha et al., 2019).

Figure 3
Synthesis scheme for 1

Figure 2
The crystal packing of 1, viewed along the a-axis direction.  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.38 e Å −3 Δρ min = −0.34 e Å −3 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. data reports data-2 IUCrData (2021). 6, x210322