Crystal structure of 2-cyano-3,3-bis(ethylsulfanyl)-N-o-tolylacrylamide

In the molecule of the title compound, the central S2C=C(CN)C moiety is planar (r.m.s. deviation = 0.029 Å). The C=O and C—CN groups are trans to each other across their common C—C bond. In the crystal, one classical and two ‘weak’ hydrogen bonds combine with borderline N⋯N and S⋯S contacts to form layers parallel to (10).


Chemical context
The synthesis of ketene S,S-acetals as potential starting materials for the preparation of novel classes of heterocycles has attracted much attention (Elgemeie et al. 2009(Elgemeie et al. , 2015. As part of a research program for preparing new classes of antimetabolites (Elgemeie et al. 2016(Elgemeie et al. , 2017a, we have recently reported successful approaches for syntheses of pyridine, pyrimidine and mercaptopurine analogues by the reaction of cyanoketene dithioacetals with active methylene compounds (Elgemeie et al., 2003(Elgemeie et al., , 2006(Elgemeie et al., , 2017b. In a continuation of this research, we report here a novel cyanoketene dithioacetal (1). Product (1) was prepared by the reaction of 2-cyano-N-(otolyl)acetamide with carbon disulfide in the presence of sodium ethoxide followed by alkylation with ethyl iodide. The structure of (1) was originally based on its spectroscopic data and elemental analysis (see Experimental). In order to establish the structure of the compound unambiguously, the crystal structure was determined.

Figure 2
Packing diagram of compound (1) viewed perpendicular to (102). Hydrogen bonds are drawn as thick dashed bonds, with other contacts (see text) as thin dashed bonds. H atoms not involved in hydrogen bonds have been omitted for clarity.

Figure 1
The structure of compound (1) in the crystal, with ellipsoids at the 50% probability level. Only one position of the disordered ethyl group C14/ C15 is shown.
S) 2 C C(CN)C O gave six hits (MTBCEY, NUCFEW, SESHUT10, SESHUT11, ZAMQUZ, ZEDJEX). In all cases the C O and C-CN groups are mutually trans, as in the title compound.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. The ethyl group C14/15 is disordered over two positions with relative occupancy 0.721 (7)/ 0.279 (7). Appropriate restraints were employed to improve refinement stability, but the dimensions of disordered groups should be interpreted with caution.