Synthesis, molecular structure and Hirshfeld surface analysis of (4-methoxyphenyl)[2-(methylsulfanyl)thiophen-3-yl]methanone

The title molecule is substantially twisted, with a dihedral angle of 43.70 (2)° between the 2-(methylsulfanyl)thiophene and 4-methoxyphenyl rings. In the crystal, molecules are linked through C—H⋯O interactions, forming a bifurcated layer stacking along the b-axis direction enclosing (10) ring motifs.


Chemical context
Thiophenes are five-membered sulfur-containing heterocyclic compounds with important applications in areas such as agrochemistry, pharmaceuticals, molecular electronics, liquid crystalline materials and corrosion inhibition. Thiophenes are also important building blocks in organic synthesis. Their aromatic character gives enough stabilization to allow the manipulation of various substituents (Mishra et al., 2011). -Oxoketene thioacetals are powerful building blocks for the synthesis of numerous heterocyclic scaffolds, where the carbonyl carbon generally provides hard centers and the carbon-bearing methylsulfanyl group acts as a soft electrophilic center (Junjappa et al., 1990). This synthetic building block was used for the synthesis of (4-methoxyphenyl) [2-(methylsulfanyl)thiophen-3-yl]methanone (Pradeepa Kumara et al., 2016).

Figure 3
Packing for of the title compound viewed along the b axis.

Synthesis and crystallization
To -oxoketene dithioacetal (0.1 mol) and 1,4-dithiane-2,5diol (0.05 mol) in dry ethanol (10 mL), anhydrous potassium carbonate (0.12 mol) was added. The reaction mixture was refluxed on a water bath for 30 minutes (the condenser being protected by a calcium chloride guard tube). After completion of the reaction (monitored by TLC), the catalyst was filtered off and washed with fresh ethanol. The combined ethanol solution was removed on a rotary evaporator to obtain a viscous liquid. The crude product was purified by column chromatography using silica gel with 5% ethyl acetate and petroleum ether to yield the title compound as a yellow solid product, which was recrystallized from dichloromethane solution.   The relative contributions (%) to the Hirshfeld surface for the various contacts.

Figure 4
Hirshfeld surface for the title compound mapped over d norm in the range À0.2106 to 1.2279 a.u. highlighting the C-HÁ Á ÁO intermolecular interactions.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. All hydrogen atoms were placed at calculated positions and refined using a riding model with C-H = 0.93 Å and U iso (H) = 1.2U eq (C) for aromatic ring atoms and with C-H = 0.96 Å with U iso (H) = 1.5U eq (C) for methyl groups.