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West Nile virus (WNV) is among the other four flavivirus genus, rapidly spreading worldwide. The number of cases increases globally as there are no clinically available approved drugs and vaccines against this disease. Based on our previous finding related to a flavivirus, a series of spiropyrrolidine derivatives were regioselectively synthesized via [3+2]-cycloaddition reaction of three components between isatins, sarcosine, and (E)-3,5-bis (arylidene)-4-piperidones. The yield of synthesized compounds was in a range between 81–95%. The structures of all the synthesized compounds were characterized using FT-IR, 1D- and 2D-NMR, and HRMS. Molecular docking studies of spiropyrrolidines on NS2B-NS3 protease were done to understand and explore the ligand-receptor interactions and hypothesize the drug's refinements. The inhibition of NS2B-NS3 protease has been considered a promising strategy because this enzyme is responsible for the viral replication process. Among them, compound 5c shows an excellent binding affinity with ‒7.71 kcal/mol free binding energy and an inhibition constant of 1.73 μM. It also showed the binding orientation into the active site of WNV NS2B-NS3 protease on Asn84, Tyr1161, Gly1151, and Gly1153.

Alzheimer's disease (AD) is a chronic disease that is multifactorial. Its underlying cause and mechanisms are yet to be fully understood and numerous research are underway to develop more effective drug candidates. This research explores the synthesis of an indazole-containing novel drug targeting AD, particularly by inhibiting cholinesterase activity. Among the 17 indazole derivatives synthesized in this study, compound 4q was demonstrated to have potent and selective butyrylcholinesterase (BChE) inhibitory activity. Molecular docking simulations revealed that the binding of 4q with BChE was through hydrophobic and polar interactions. It was also found to easily permeate through the blood-brain-barrier via an in vitro model and is non-toxic when tested against SH-SY5Y cells. [ABSTRACT FROM AUTHOR]

In the title compound, C24H25N3O5, the ethoxy group is disordered over two orientations in a 0.853 (14):0.147 (14) ratio. The benzimadazole ring system (r.m.s. deviation = 0.016 Å) makes a dihedral angle of 35.47 (7)° with the attached benzene ring. The pyrrolidine ring adopts an envelope conformation with a methylene C atom as the flap. In the crystal, inversion dimers linked by pairs of O—H...N hydrogen bonds generate R22(16) loops. C—H...O interactions link the dimers into a three-dimensional network.

The asymmetric unit of the title compound, C27H32N4O4·H2O, contains two independent benzimidazole-5-carboxylate molecules and two water molecules. In both main molecules, the pyrrolidine rings are in an envelope conformation with a methylene C atom as the flap. The morpholine rings adopt chair conformations. Both benzimidazole rings are essentially planar, with maximum deviations of 0.008 (1) Å, and form dihedral angles of 37.65 (6) and 45.44 (6)° with the benzene rings. In one molecule, an intramolecular C—H...O hydrogen bond forms an S(7) ring motif. In the crystal, O—H...O and O—H...N hydrogen bonds connect pairs of main molecules and pairs of water molecules into two independent centrosymmetric four-compoment aggregates. These aggregates are connect by C—H...O hydrogen bonds leading to the formation of a three-dimensional network, which is stabilized by C—H...π interactions.

In the title compound, C23H17F3N2O3, an intramolecular C—H...F hydrogen bond generates an S(6) ring motif. The essentially planar 1H-benzimidazole ring system [maximum deviation = 0.021 (2) Å] forms dihedral angles of 25.00 (10) and 62.53 (11)° with the trifluoromethoxy-substituted benzene and phenyl rings, respectively. The twist of the ethyl acetate group from the least-squares plane of the 1H-benzimidazole ring system is defined by a C(=O)—O—C—C torsion angle of 79.5 (3)°. In the crystal, molecules are linked into a two-dimensional network parallel to the bc plane by weak C—H...N and C—H...O hydrogen bonds. Weak C—H...π interactions also observed.

In the title compound, C22H17ClN2O2, the essentially planar benzimidazole ring system [maximum deviation = 0.012 (2) Å] forms dihedral angles of 28.69 (6) and 63.65 (7)°, respectively, with the phenyl and chloro-substituted benzene rings. The dihedral angle between the phenyl and benzene rings is 64.23 (8)°. In the crystal, molecules are linked into a zigzag chain along the a axis by intermolecular C—H...O hydrogen bonds. C—H...π interactions are also present.

In the title compound, C22H17BrN2O2, the benzimidazole ring system is essentially planar, with a maximum deviation of 0.017 (1) Å, and forms dihedral angles of 27.79 (6) and 64.43 (6)° with the phenyl and bromo-substituted benzene rings, respectively. In the crystal, molecules are linked into one-dimensional chains along the a axis by weak C—H...O hydrogen bonds. Weak intermolecular C—H...π interactions are also present.

In the title compound, C15H14N2O4, the dihedral angle between the benzene and phenyl rings is 73.20 (6)°. An intramolecular N—H...O hydrogen bond forms an S(6) ring motif. In the crystal, molecules are linked by N—H...O and C—H...O hydrogen bonds into a layer parallel to the bc plane.

The asymmetric unit of the title compound, C24H27N3O4, contains two molecules, A and B. The benzimidazole rings are essentially planar [maximum deviations = 0.0144 (10) and 0.0311 (8) Å in A and B, respectively]. The dihedral angle between the benzimidazole mean plane and its attached benzene ring is 36.90 (5) ° for molecule A and 51.40 (5) ° for molecule B. In both molecules, the pyrrolidine ring adopts an envelope conformation with a C atom as the flap. In molecule B, the flap C atom is disordered over two positions in a 0.711 (6):0.289 (6) ratio. In the crystal, C—H...O interactions link the molecules, generating [100] chains. The crystal packing also features weak π–π interactions between the imidazole and benzene rings [centroid–centroid distances = 3.8007 (7) and 3.8086 (7) Å] and between the benzene rings [centroid–centroid distance = 3.7001 (7) Å] and C—H...π interactions involving the benzene rings.

In the title compound, C23H25N3O3, the benzimidazole ring system is essentially planar [maximum deviation = 0.0240 (18) Å]. The mean plane through this ring system forms a dihedral angle of 42.23 (7)° with the benzene ring. The pyrrolidine ring is in an envelope conformation with the flap atom disordered over two sites with occupancies of 0.813 (11) and 0.187 (11). In the crystal, weak C—H...O hydrogen bonds form R22(10) ring motifs, which are connected by further C—H...O interactions, forming ribbons along the b axis. The crystal structure is further stabilized by weak π–π interactions involving the imidazole and benzene rings of the benzimidazole ring system [centroid–centroid distances = 3.6788 (11) and 3.6316 (10) Å] and weak C—H...π interactions.

In the title compound, C24H25N3O5, the benzimidazole and benzodioxole ring systems are each approximately planar [maximum deviations = 0.043 (1) and 0.036 (1) Å, respectively]. Their mean planes form a dihedral angle of 42.85 (4)°. The pyrrolidine ring has an envelope conformation with one of the methylene C atoms forming the flap. In the crystal, weak C—H...O hydrogen bonds link the molecules into a three-dimensional network. The crystal packing is further stabillized by weak π–π interactions between the benzene rings within the benzimidazole ring system [centroid–centroid distance = 3.7955 (7) Å]. A weak C—H...π interaction involving the benzodioxole ring is also present.

In the title compound, C24H27N3O5·H2O, the essentially planar benzimidazole ring system [maximum deviation = 0.020 (1) Å] forms dihedral angles of 54.10 (11) and 67.79 (6)°, respectively, with the mean plane of pyrrolidin-2-one ring and the benzene ring. The pyrrolidin-2-one ring adopts an envelope conformation with one of the methylene C atoms at the flap. An intramolecular C—H...π interaction is observed. In the crystal, O—H...O and O—H...N hydrogen bonds link the two components into a double-tape structure along the a axis. The crystal packing is further stabilized by weak π–π stacking [centroid–centroid distance = 3.6632 (9) Å] and C—H...O interactions.

In the title compound, C23H22N4O4, the essentially planar [maximum deviation = 0.022 (1) Å] benzimidazole ring system forms dihedral angles of 86.16 (7) and 37.38 (6)°, respectively, with the imidazole and benzene rings. The dioxolane ring adopts an envelope conformation with the methylene C atom at the flap. In the crystal, C—H...O and C—H...N interactions link the molecules into a ribbon along the a axis. The crystal packing is further stabilized by weak π–π stacking interactions [centroid–centroid distances = 3.5954 (8) and 3.7134 (8) Å] and C—H...π interactions.

In the title compound, C23H24N4O5, the essentially planar benzimidazole ring system [maximum deviation = 0.008 (2) Å] forms a dihedral angle of 39.22 (7)° with the attached nitrobenzene ring. The pyrrolidin-2-one ring adopts an envelope conformation with a C atom as the flap. In the crystal, molecules are connected by C—H...O interactions, forming sheets propagating in (011). The crystal packing also features weak π–π stacking interactions [centroid–centroid = 3.6746 (12) Å].

In the title compound, C28H20BrNO3S, the thiazolidine, pyrrolidine and two five-membered carbocyclic rings are in envelope conformations. The bromo-bound phenyl ring forms dihedral angles of 61.97 (18) and 88.30 (17)° with the other two benzene rings. The two benzene rings form a dihedral angle of 30.3 (2)°. The molecular structure features an intramolecular C—H...O hydrogen bond, which generates an S(6) ring motif. In the crystal, molecules are linked into inversion dimers by pairs of C—H...O hydrogen bonds.

In the title compound, C22H21BrN4O2·H2O, the two pyrazole rings are essentially planar [maximum deviations 0.002 (1) and 0.002 (1) Å], and form a dihedral angle of 73.46 (9)°. The dihedral angle between the benzene rings is 29.33 (7)°. In the crystal, molecules are connected via C—H...O and O—H...N hydrogen bonds, forming layers in the ab plane.

In the title compound, C15H18N4O4, the 1H-imidazole ring forms a dihedral angle of 67.12 (8)° with the benzene ring. An S(6) ring motif is formed via an intramolecular N—H...O hydrogen bond. In the crystal, neighbouring molecules are linked by a pair of intermolecular N—H...N hydrogen bonds, forming an inversion dimer. The dimers are further linked by a pair of C—H...O hydrogen bonds, leading to the formation of chain along [021]. A C—H...π interaction involving the centroid of the benzene ring is also observed between the chains.

In the title compound, C27H20ClNO3, the two cyclopentane rings adopt envelope conformations. The pyrrolidine ring also adopts an envelope conformation (with the spiro C atom as the flap) and its least-squares plane (fitted to five atoms) makes dihedral angles of 66.50 (9), 77.36 (8) and 73.76 (8)° with the chlorobenzene ring and the two 2,3-dihydro-1H-indene ring systems, respectively. The molecular conformation is stabilized by an intramolecular C—H...O hydrogen bond, which generates an S(6) ring motif. In the crystal, molecules are linked by C—H...O hydrogen bonds into chains running parallel to the [001] direction.