The title compound, C9H7NO2S crystallizes with two independent mol-ecules (A and B) in the asymmetric unit with Z = 8. Both mol-ecules are almost planar with a dihedral angle between the isoxazole and thio-phen rings of 3.67 (2)° in mol-ecule A and 10.00 (1) ° in mol-ecule B. The packing of mol-ecules A and B is of an ABAB⋯ type along the b-axis direction, the configuration about the C=C bond is Z. In the crystal, the presence of C-H⋯O, C-H⋯ N and π-π inter-actions [centroid-centroid distances of 3.701 (2) and 3.766 (2) Å] link the mol-ecules into a three-dimensional architecture. https://www.selleckchem.com/ An analysis of Hirshfeld surfaces shows the importance of C-H⋯O and C-H⋯N hydrogen bonds in the packing mechanism of the crystalline structure.The title compounds, 8-1-[3-(cyclo-pent-1-en-1-yl)benz-yl]piperidin-4-yl-2-meth-oxy-quinoline, C27H30N2O (I), and 8-4-[3-(cyclo-pent-1-en-1-yl)benz-yl]piperazin-1-yl-2-meth-oxy-quinoline, C26H29N3O (II), differ only in the nature of the central six-membered ring piperidine in I and piperazine in II. They are isoelectronic (CH cf. N) and isotypic; they both crystallize in the triclinic space group P with very similar unit-cell parameters. Both mol-ecules have a curved shape and very similar conformations. In the biaryl group, the phenyl ring is inclined to the cyclo-pentene mean plane (r.m.s. deviations = 0.089 Å for I and 0.082 Å for II) by 15.83 (9) and 13.82 (6)° in I and II, respectively, and by 67.68 (6) and 69.47 (10)°, respectively, to the mean plane of the quinoline moiety (r.m.s. deviations = 0.034 Å for I and 0.038 Å for II). The piperazine ring in I and the piperidine ring in II have chair conformations. In the crystals of both compounds, mol-ecules are linked by C-H⋯π inter-actions, forming chains in I and ribbons in II, both propagating along the b-axis direction. The principal contributions to the overall Hirshfeld surfaces involve H⋯H contacts at 67.5 and 65.9% for I and II, respectively. The major contribution to the inter-molecular inter-actions in the crystals is from dispersion forces (E dis), reflecting the absence of classical hydrogen bonds.In the title compound, C25H22N2O3S·0.04H2O, the central cyclo-hexane ring adopts a chair conformation. In the crystal, mol-ecules are linked by N-H⋯O, C-H⋯O, and C-H⋯N hydrogen bonds, forming the mol-ecular layers parallel to the bc plane, which inter-act by the van der Waals forces between them. A Hirshfeld surface analysis indicates that the contributions from the most prevalent inter-actions are H⋯H (41.2%), C⋯H/H⋯C (20.3%), O⋯H/H⋯O (17.8%) and N⋯H/H⋯N (10.6%).The title sterically congested piperazine derivative, C20H27FN2O2, was prepared using a modified Bruylants approach. A search of the Cambridge Structural Database identified 51 compounds possessing an N-tert-butyl piperazine substructure. Of these only 14 were asymmetrically substituted on the piperazine ring and none with a synthetically useful second nitro-gen. Given the novel chemistry generating a pharmacologically useful core, determination of the crystal structure for this compound was necessary. The piperazine ring is present in a chair conformation with di-equatorial substitution. Of the two N atoms, one is sp 3 hybridized while the other is sp 2 hybridized. Inter-molecular inter-actions resulting from the crystal packing patterns were investigated using Hirshfeld surface analysis and fingerprint analysis. Directional weak hydrogen-bond-like inter-actions (C-H⋯O) and C-H⋯π inter-actions with the dispersion inter-actions as the major source of attraction are present in the crystal packing.In the title compound, C33H26N4O4, the two fused five-membered rings and their N-bound aromatic substituents form a pincer-like motif. The relative conformations about the three chiral carbon atoms are established. In the crystal, a combination of C-H⋯O and C-H⋯N hydrogen bonds and C-H⋯π(ring) inter-actions leads to the formation of layers parallel to the bc plane. A Hirshfeld surface analysis indicates that the most significant contributions to the crystal packing are from H⋯H (44.3%), C⋯H/H⋯C (29.8%) and O⋯H/H⋯O (15.0%) contacts.In the title compounds C23H21ClN2O3 [I, namely 1-(4-chloro-phen-yl)-4-(4-methyl-phen-yl)-3,8-dioxo-1,2,5,6,7,8-hexa-hydro-quine-3-carb-oxy-lic acid] and C24H22N2O3 [II, namely 4-(4-meth-oxy-phen-yl)-1-(4-methyl-phen-yl)-2,5-dioxo-1,2,5,6,7,8-hexa-hydro-quinoline-3-carbo-nitrile], each of the cyclo-hexene and di-hydro-pyridine rings of the 1,2,5,6,7,8-hexa-hydro-quinoline moieties adopts a twisted-boat conformation. The asymmetric units of both compounds I and II consist of two independent mol-ecules (A and B). In II A, three carbon atoms of the cyclo-hexene ring are disordered over two sets of sites in a 0.670 (11)0.330 (11) occupancy ratio. In the crystal of I, mol-ecules are linked through classical N-H⋯O hydrogen bonds, forming inversion dimers with an R 2 2(8) ring motif and with their mol-ecular planes parallel to the crystallographic (020) plane. Non-classical C-H⋯O hydrogen-bonding inter-actions connect the dimers, resulting in a three-dimensional network. In the crystal of II, mol-ecules are linked by C-H⋯N, C-H⋯O and C-H⋯π inter-actions, forming a three-dimensional network.In the title compound, C24H20ClNO2, the mean planes of 4-chloro-phenyl, 2-methyl-phenyl and phenyl-ene rings make dihedral angles of 62.8 (2), 65.1 (3) and 15.1 (2)°, respectively, with the 5-methyl-1,2-oxazole ring. In the crystal, mol-ecules are linked by inter-molecular C-H⋯N, C-H⋯Cl, C-H⋯π contacts and π-π stacking inter-actions between the phenyl-ene groups. Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H⋯H (48.7%), H⋯C/C⋯H (22.2%), Cl⋯H/H⋯Cl (8.8%), H⋯O/O⋯H (8.2%) and H⋯N/N⋯H (5.1%) inter-actions.The crystal structures of three inter-mediate compounds in the synthesis of 8-bromo-2,3,4,5-tetra-hydro-1,3,3-tri-methyl-dipyrrin are reported; 4-bromo-2-formyl-1-tosyl-1H-pyrrole, C12H10BrNO3S, (E)-4-bromo-2-(2-nitro-vin-yl)-1-tosyl-1H-pyrrole, C13H11BrN2O4S, and 6-(4-bromo-1-tosyl-pyrrol-2-yl)-4,4-dimethyl-5-nitro-hexan-2-one, C19H23BrN2O5S. The compounds show multitudinous inter-molecular C-H⋯O inter-actions, with bond distances and angle consistent in the series and within expectations, as well as varied packing types. The merits of collecting data beyond the standard resolution usually reported for small mol-ecules are discussed.