Crystal structure and Hirshfeld surface analysis of 2,2,2-trichloro-N,N-bis{[(1RS,4SR)-1,4-dihydro-1,4-epoxynaphthalen-1-yl]methyl}acetamide

In the crystal, molecules are linked by C—H⋯O hydrogen bonds, forming layers parallel to the (001) plane. These layers of molecules are connected by C—H⋯π interactions along the c-axis direction. Interlayer van der Waals and interhalogen interactions stabilize the packing.


Chemical context
In recent years, the IMDAF cycloaddition (the intramolecular furan Diels-Alder reaction) in combination with other known reactions in a tandem or sequential manner is pursued for the construction of several important bicyclic or polycyclic compounds, including natural ones (for some reviews on this topic, see: Zubkov et al., 2005;Takao et al., 2005;Juhl et al., 2009;Padwa et al., 2013;Parvatkar et al., 2014;Krishna et al., 2021). Cascade sequences comprising two or more successive [4 + 2] cycloaddition steps are a powerful and frequently used protocol in modern syntheses aimed at constructing cyclohexene derivatives thanks to their exceptional chemoselectivity, regioselectivity, diastereoselectivity, and capability to create more than four chiral centers in a single synthetic step (Criado et al., 2010(Criado et al., , 2013. It has been shown previously that the Diels-Alder reaction of bis-dienes with derivatives of maleic acid, esters of acetylene dicarboxylic acid and hexa-fluoro-2-butyne proceeds in all cases diastereo-and chemoselectively and leads, depending on the temperature, to annelated diepoxynaphthalenes of the 'domino' or 'pincer' type (Borisova et al., 2018a,b;Grudova et al., 2020;Kvyatkovskaya et al., 2020Kvyatkovskaya et al., , 2021. In order to expand the limits of the applicability of the IMDAF strategy, we tested in this study dehydrobenzene generated in situ in the role of dienophile. It was demonstrated that the products of the parallel [4 + 2] cycloaddition of two aryne moieties to both the furan fragments of the bis-diene system (Fig. 1, 1 and 2) prevails over the adduct (3) of the IMDAF reaction (Fig. 1).

Supramolecular features and Hirshfeld surface analysis
In the crystal, hydrogen bonds of the C-HÁ Á ÁO type link the molecules, generating layers parallel to the (001) plane (Table 1; Figs. 3,4,5 and 6). These layers are connected by C-HÁ Á Á interactions (C13-H13AÁ Á ÁCg8; The molecule of the title compound 1 with atom-labeling scheme and displacement ellipsoids drawn at the 30% probability level. Hydrogen atoms are shown as spheres of arbitrary radius.
the centroid of the C24A/C25-C28/C28A aromatic ring. The intermolecular interactions in the crystal of the title compound (Table 2) were quantified using Hirshfeld surface analysis (Spackman & Jayatilaka, 2009) and the associated two-dimensional fingerprint plots (McKinnon et al., 2007) were generated. The calculations and visualization were performed using CrystalExplorer17 (Turner et al., 2017). The three-dimensional Hirshfeld surface mapped over d norm in the range À0.1862 (red) to +1.4233 (blue) a.u. is shown in Fig. 7. The short and long contacts are indicated as red and blue spots, respectively, on the Hirshfeld surfaces, and contacts with distances approximately equal to the sum of the van der Waals radii are represented as white spots. The ClÁ Á ÁH and C-HÁ Á ÁO interactions, which play a key role in the molecular packing, can be correlated with the bright-red patches near Packing viewed along the b-axis direction with the intermolecular C-HÁ Á ÁO hydrogen bonds and C-HÁ Á Á interactions depicted by dashed lines.

Figure 6
Packing viewed along the c-axis direction with the intermolecular C-HÁ Á ÁO hydrogen bonds and C-HÁ Á Á interactions depicted by dashed lines.

Figure 4
Packing viewed along the a-axis direction with the intermolecular C-HÁ Á ÁO hydrogen bonds and C-HÁ Á Á interactions depicted by dashed lines.

Table 2
Summary of short interatomic contacts (Å ) in the title compound (1).
In the crystal of IQOTOA, the asymmetric unit consists of two crystallographically independent molecules. In both molecules, the pyrrolidine and tetrahydrofuran rings adopt  Table 3 Percentage contributions of interatomic contacts to the Hirshfeld surface for the title compound (1).

Figure 7
Hirshfeld surface of the title molecule 1 mapped with d norm .  envelope conformations. In the crystal, molecules are linked in pairs by C-HÁ Á ÁO hydrogen bonds. These pairs form a tetrameric supramolecular motif, leading to molecular layers parallel to the (100) plane formed by C-HÁ Á Á and C-BrÁ Á Á interactions. OMUTAU also crystallizes with two independent molecules in the asymmetric unit. In the central ring systems of both molecules, the tetrahydrofuran rings adopt envelope conformations, the pyrrolidine rings adopt twisted-envelope conformations and the six-membered ring is in a boat conformation. In both molecules, the nine-membered groups attached to the central ring system are essentially planar. In the crystal, strong intermolecular O-HÁ Á ÁO hydrogen bonds and weak intermolecular C-HÁ Á ÁO contacts link the molecules, forming a three-dimensional network. In addition, weakstacking interactions between the pyrrolidine rings are observed. OMEMAX again crystallizes with two molecules in the asymmetric unit of the unit cell. In both molecules, the tetrahydrofuran rings adopt envelope conformations with the O atoms as the flaps and the pyrrolidine rings also adopt envelope conformations. In the crystal, molecules are linked by weak C-HÁ Á ÁO hydrogen bonds, forming sheets lying parallel to the (001) plane. These sheets are connected only by weak van der Waals interactions. In the crystal of IMUBIE, the molecules are linked into dimers by pairs of C-HÁ Á ÁO hydrogen bonds, thus generating R 2 2 (18) rings. The crystal packing is dominated by HÁ Á ÁH, BrÁ Á ÁH, HÁ Á Á and BrÁ Á Á interactions. In the crystal structures of IQOTOA, OMUTAU, OMEMAX, AGONUH, TIJMIK, YAXCIL, UPAQEI and ERIVIL, the molecules are predominantly linked by C-HÁ Á ÁO hydrogen bonds, giving various hydrogen-bonding pattern connectivities. In the crystal of AGONUH, the molecules are connected in zigzag chains running along the b-axis direction. In TIJMIK, two types of C-HÁ Á ÁO hydrogen bonds are found, viz. R 2 2 (20) and R 4 4 (26) rings, with adjacent rings running parallel to the ac plane. Additionally, C-HÁ Á ÁO hydrogen bonds form a C(6) chain, linking the molecules in the b-axis direction. In the crystal of ERIVIL, the molecules are connected into R 2 2 (8) and R 2 2 (14) rings along the b-axis direction. In MIGTIG, the molecules are linked only by weak van der Waals interactions.

Synthesis and crystallization
CsF (1.7 g, 0.011 mol) was added to 2,2,2-trichloro-N,N-bis(furan-2-ylmethyl)acetamide (0.0022 mol) dissolved in dry CH 3 CN (20 mL). Then an equivalent of 2-(trimethylsilyl)phenyl trifluoromethanesulfonate (0.54 mL, 0.022 mol) was added to the solution under an argon atmosphere. The mixture was refluxed for 4 h (TLC control). After that, one more portion of 2-(trimethylsilyl)phenyl trifluoromethanesulfonate (0.27 mL, 0.011 mol) and CsF (1.7 g, 0.011 mol) was added to the mixture, repeating all procedures again. After the mixture was cooled, CsF was filtered off through a thin layer of SiO 2 , and the resulting solution was concentrated under reduced pressure. The residue (brown oil) was separated using column chromatography on silica gel (a mixture EtOAc/ hexane = 1/25 as eluent) to give compounds 1-3 in the ratio

2,2,2-Trichloro-N,N-bis{[(1RS,4SR)-1,4-dihydro-1,4-epoxynaphthalen-1-yl]methyl}acetamide
Crystal data 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.