tert-Butyl 2-sulfanylidene-2,3-dihydro-1H-imidazole-1-carboxylate

In the title molecule, C8H12N2O2S, the imidazole ring forms a dihedral angle of 5.9 (2)° with the mean plane of the carboxylate group. In the crystal, molecules are linked by pairs of N—H⋯S hydrogen bonds, forming inversion dimers.

In the title molecule, C 8 H 12 N 2 O 2 S, the imidazole ring forms a dihedral angle of 5.9 (2) with the mean plane of the carboxylate group. In the crystal, molecules are linked by pairs of N-HÁ Á ÁS hydrogen bonds, forming inversion dimers.
Data collection: CrysAlis PRO (Agilent, 2011); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97.  (Kasraee (2002); Kasraee et al., 2005). Ergothioneine has a significant effect on inhibiting tyrosinase enzyme activity, resulting from the presence of the sulfur substituent in the imidazole ring (Liao et al., 2012). It shows that molecules with a 2-mercaptoimidazole group have potential as skin whitening agents. In this regard, we report here the synthesis and crystal structure of the title compound. The molecular structure of the title compound is shown in Fig. 1.

Experimental
To a mixture of 2-mercaptoimidazole (351 mg, 3.5 mmole) and potassium carbonate (968 mg, 7 mmole) in 7 ml of N,Ndimethylformamide was added di-tert-butyl dicarbonate (1.1 ml, 5.2 mmol). The reaction mixture was stirred at 298 K for 24 h under N 2 atmosphere. The resulting mixture was partitioned between ethyl acetate (40 ml) and H 2 O (20 ml). The organic layer was dried over MgSO 4 and concentrated in vacuo. The residue was separated by chromatography over silica gel and eluted with hexane/ethyl acetate (3/7) to afford 297 mg of the title compound (I) in 42% yield. Single crystals suitable for X-ray measurements were obtained by recrystallization from a dichloromethane/hexane solution of the title compound at room temperature. Anal. Calcd for C 8 H 12 N 2 O 2 S: C, 47.98; H, 6.04; N, 13.99; Found: C, 47.86; H, 6.14; N, 13.92.

Refinement
All H atoms were placed in geometrically idealized positions and treated as riding on their parent atoms, with C-H = 0.93 -0.96 Å, N-H = 0.86 Å and U iso (H) > 1.2U eq (C,N) or 1.5 U eq (C methyl ).

tert-Butyl 2-sulfanylidene-2,3-dihydro-1H-imidazole-1-carboxylate
Crystal data 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.