Crystal structures of (E)-3-(furan-2-yl)-2-phenyl-N-tosylacrylamide and (E)-3-phenyl-2-(m-tolyl)-N-tosylacrylamide

In the title N-tosylacrylamide compounds, (I) and (II), the conformation about the C=C bond is E. In (I), the furan, phenyl and 4-methylbenzene rings are inclined to the acrylamide mean plane [–NH—C(= O)—C=C–] by 26.47 (11), 69.01 (8) and 82.49 (9)°, respectively. In (II), the phenyl, and 3-methyl and 4-methylbenzene rings are inclined to the acrylamide mean plane by 11.61 (10), 78.44 (10) and 78.24 (10)°, respectively. In the crystals of both compounds, molecules are linked by pairs of N—H⋯O hydrogen bonds, forming inversion dimers with (8) ring motifs.


Chemical context
The Cu-catalysed azide-alkyne cycloaddition (CuAAC) reaction constitutes one of the most interesting examples of the click reaction (Bae et al., 2005;Cheng et al., 2012;Mondal & Pan, 2015). Trisubstituted alkenes are commonly found in the molecular skeleton of natural products and bioactive substances, and they are important building blocks in organic chemistry (Zhu et al., 2012;Manikandan & Jeganmohan, 2015). Therefore, it is highly desirable to develop new efficient and general methods for the stereoselective synthesis of trisubstituted alkenes (Ram & Tittal, 2014;Bae et al., 2005). As part of our work on the application of the CuAAC reaction (Cheng et al., 2012), we report herein on the synthesis and crystal structures of the title compounds, (I) and (II).

Supramolecular features
In the crystal of both compounds, molecules are linked by pairs of N-HÁ Á ÁO hydrogen bonds (Tables 1 and 2), forming inversion dimers with R 2 2 (8) ring motifs, as shown in Fig. 4 for (I) and Fig. 5 for (II). In (I), the dimers are reinforced by C-HÁ Á ÁO hydrogen bonds and linked by C-HÁ Á Á interactions (Table 1), forming chains propagating along [011]. In the crystal of (II), the dimers are linked via C-HÁ Á ÁO hydrogen bonds, forming chains propagating along [100]. There is also a C-HÁ Á Á interaction present, linking the chains to form layers lying parallel to (010).

Database survey
A search of the Cambridge Structural Database (Version 5.37, update February 2016;Groom et al., 2016)   The molecular structure of compound (II), showing the atom labelling and displacement ellipsoids drawn at the 50% probability level. The intramolecular C-HÁ Á Á interaction is shown by the blue dashed arrow (see Table 2).

Figure 1
The molecular structure of compound (I), showing the atom labelling and displacement ellipsoids drawn at the 50% probability level.

Figure 3
A view of the overlap of molecules (I) (blue) and (II) (red).
N-(phenylsulfonyl)acrylamide yielded five hits. Four of these compounds involve the 4-methylbenzenesulfonyl group and one compound involves a phenylsulfonyl group. This later compound, 2-(4-chlorophenyl)-3-(2-furyl)-N-(phenylsulfonyl)acrylamide (BIZGOI; Yu & Cao, 2014), is very similar to compound (I). The principal difference in the conformation of this molecule with respect to that of compound (I) is the dihedral angle involving the pyran ring and the adjacent aromatic ring, a phenyl ring in (I) and a chlorobenzene ring in BIZGOI; this angle is 66.18 (11) in (I) but 88.84 (13) in BIZGOI. In the crystal of BIZGOI, molecules are linked by pairs of N-HÁ Á ÁO hydrogen bonds, forming inversion dimers with an R 2 2 (8) ring motif, similar to the arrangement in the crystals of compounds (I) and (II).

Synthesis and crystallization
Compound (I): 4-methylbenzenesulfonyl azide (4.5 mmol), CuI (5.7 mg, 0.03 mmol), Et 4 NI (7.7 mg, 0.03 mmol), ethynylbenzene (4.5 mmol), and furan-2-carbaldehyde (3 mmol) were suspended in CH 2 Cl 2 (5 ml) in a 10 mL Schlenk tube under nitrogen at rt. LiOH (8.64 mg, 3.6mmol) was then added, and the resulting solution was stirred at this temperature. Upon full consumption of furan-2-carbaldehyde, the reaction was quenched by saturated aqueous NH 4 Cl (5 ml) and extracted with CH 2 Cl 2 (10 ml Â 3). The combined organic layers were dried over anhydrous Na 2 SO 4 and concentrated in vacuo. The crude residue was purified by column chromatography on silica gel (n-hexane/EtOAc 5:1 v/v) to afford compound (I) as a white solid (yield: 0.79 g, 72%). Part of the purified product was redissolved in n-hexane/EtOAc and after The crystal packing of compound (I), viewed along the b-axis direction. The hydrogen bonds are shown as dashed lines (see Table 1), and for clarity only the H atoms involved in the various interactions have been included. Table 1 Hydrogen-bond geometry (Å , ) for (I).

Figure 5
The crystal packing of compound (II), viewed along the b-axis direction. The hydrogen bonds are shown as dashed lines (see Table 2), and for clarity only the H atoms involved in the various interactions have been included. slow evaporation over several days, colourless crystals suitable for analysis by X-ray diffraction were formed.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 3. H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms: C-H = 0.93-0.96 Å and N-H = 0.86 Å , with U iso (H) = 1.5U eq (C-methyl) and 1.2U eq (C,N) for other H atoms.

Hydrogen-bond geometry (Å, º)
Cg1 is the centroid of the furan ring, O4/C17-C20  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.020 Δρ max = 0.24 e Å −3 Δρ min = −0.35 e Å −3 Special details 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 esds 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 > 2sigma(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.  (11)  C5 0.0381 (9) 0.0391 (9) 0.0479 (10) −0.0021 (7) −0.0104 (7) −0.0132 (7)  0.0389 (9) 0.0418 (9) 0.0403 (9) −0.0023 (7) −0.0119 (7) −0.0067 (7)