Crystal structure and Hirshfeld surface analysis of (3aSR,6RS,6aSR,7RS,11bSR,11cRS)-2,2-dibenzyl-2,3,6a,11c-tetrahydro-1H,6H,7H-3a,6:7,11b-diepoxydibenzo[de,h]isoquinolin-2-ium trifluoromethanesulfonate

In the crystal, dimeric C—H⋯O hydrogen bonds connect pairs of cations, producing two (6) ring motifs parallel to the (001) plane. Intermolecular C—H⋯O hydrogen connections connect the cations and anions, producing a three-dimensional network.


Chemical context
Intramolecular Diels-Alder reactions (Krishna et al., 2021) are powerful tools in the arsenal of modern organic chemistry. In particular, the IMDAF cycloaddition (the intramolecular furan Diels-Alder reaction) based on renewable starting materials (e.g. furfural, furfuryl alcohol, etc.), is frequently used in natural product synthesis and in many other practically useful applications (for reviews on the topic, see: Zubkov et al., 2005;Takao et al., 2005;Juhl et al., 2009;Padwa et al., 2013;Parvatkar et al., 2014). Cascade sequences including two or more successive [4 + 2] cycloaddition steps to furan moieties are less known because of difficulties in accessing the starting materials. However, these tandem strategies open up an easy way for the construction of polyfunctional naphthalene derivatives, which can be obtained in one synthetic step. At the same time, it becomes possible to create four or more chiral centres in one synthetic stage with exceptional chemo-, regioand diastereoselectivity (Criado et al., 2010(Criado et al., , 2013Zubkov et al., 2012Zubkov et al., , 2014. Previously, it was shown that the [4 + 2] cycloaddition of bis-furyldienes with derivatives of maleic acid, esters of acetylene dicarboxylic acid or hexafluoro-2butyne proceeds in all cases with excellent diastereo-and chemoselectivity, and leads, depending on the temperature, to annelated diepoxynaphthalenes of the 'domino' or 'pincer' type (Borisova et al., 2018a,b).
In order to expand the limits of the applicability of the IMDAF strategy, during the current study we tested dehydrobenzene generated in situ in the role of a dienophile. It ISSN 2056-9890 was found that N-benzyldifurfurylamine under the action of dehydrobenzene forms a multicomponent mixture, from which three major components (1-3) were isolated using column chromatography (Fig. 1). Compound 1, the most interesting from a chemical point of view, was chosen for structural analysis using diffraction data.
In general, non-covalent interactions such as hydrogen bonding, ionic and -interactions play critical roles in synthesis and catalysis, as well as in the organization of the supramolecular structures as a result of their significant contribution to the self-assembly process (Gurbanov et al., 2020a,b;Khalilov et al., 2018a,b;Ma et al., 2017aMa et al., ,b, 2020Ma et al., , 2021Mahmudov et al., 2012Mahmudov et al., , 2020Mizar et al., 2012). Thus, the interplay of non-covalent interactions has an impact on solubility (Shixaliyev et al., 2019) and other functional properties of 1.

Figure 2
The asymmetric unit of the title salt 1 with displacement ellipsoids for the non-hydrogen atoms drawn at the 30% probability level. Table 1 Hydrogen-bond geometry (Å , ).

Figure 4
Packing of the title salt 1 viewed along the a axis direction with C-HÁ Á ÁO hydrogen bonds shown as dashed lines.

Figure 5
Packing of the title salt 1 viewed along the b-axis direction with C-HÁ Á ÁO hydrogen bonds shown as dashed lines.

Figure 6
Packing of the title salt 1 viewed along the c-axis direction with C-HÁ Á ÁO hydrogen bonds shown as dashed lines.
IQOTOA, OMUTAU and OMEMAX each crystallize with two molecules in the asymmetric unit. In the crystal, molecule pairs generate centrosymmetric rings with R 2 2 (8) motifs linked by C-HÁ Á ÁO hydrogen bonds. These pairs of molecules form a tetrameric supramolecular motif, leading to molecular layers parallel to the (100) plane by C-HÁ Á Á and C-BrÁ Á Á interactions. Interlayer van der Waals and interhalogen interactions stabilize the molecular packing. In the crystal of OMUTAU, 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 of the nine-membered groups of molecules are observed. In the crystal of OMEMAX, molecules are linked by weak C-HÁ Á ÁO hydrogen bonds, forming sheets lying parallel to the (002) plane. These sheets are connected only by weak van der Waals interactions. In the crystal of IMUBIE, the molecules  Table 2 Summary of short interatomic contacts (Å ) in the title salt 1.

Figure 7
Hirshfeld surface of the title molecule 1 mapped over d norm .  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 describing different hydrogen-bonding pattern connectivities. In the crystal of AGONUH, the molecules are connected into zigzag chains running along the b-axis direction. In TIJMIK, two types of C-HÁ Á ÁO hydrogen bond motifs 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 along the b-axis direction. In the crystal of ERIVIL, molecules are connected into R 2 2 (8) and R 2 2 (14) rings along the b axis. In MIGTIG, the molecules are linked only by weak van der Waals interactions.

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.