Synthesis and dual D2 and 5-HT1A receptor binding affinities of 5-piperidinyl and 5-piperazinyl-1H-benzo[d]imidazol-2(3H)-ones

Recent advances in dopamine D2 receptor ligands in the treatment of neuropsychiatric disorders

Dopamine is a biologically active amine synthesized in the central and peripheral nervous system. This biogenic monoamine acts by activating five types of dopamine receptors (D_1-5 Rs), which belong to the G protein-coupled receptor family. Antagonists and partial agonists of D₂ Rs are used to treat schizophrenia, Parkinson's disease, depression, and anxiety. The typical pharmacophore with high D₂ R affinity comprises four main areas, namely aromatic moiety, cyclic amine, central linker and aromatic/heteroaromatic lipophilic fragment. From the literature reviewed herein, we can conclude that 4-(2,3-dichlorophenyl), 4-(2-methoxyphenyl)-, 4-(benzo[b]thiophen-4-yl)-1-substituted piperazine, and 4-(6-fluorobenzo[d]isoxazol-3-yl)piperidine moieties are critical for high D₂ R affinity. Four to six atoms chains are optimal for D₂ R affinity with 4-butoxyl as the most pronounced one. The bicyclic aromatic/heteroaromatic systems are most frequently occurring as lipophilic appendages to retain high D₂ R affinity. In this review, we provide a thorough overview of the therapeutic potential of D₂ R modulators in the treatment of the aforementioned disorders. In addition, this review summarizes current knowledge about these diseases, with a focus on the dopaminergic pathway underlying these pathologies. Major attention is paid to the structure, function, and pharmacology of novel D₂ R ligands, which have been developed in the last decade (2010-2021), and belong to the 1,4-disubstituted aromatic cyclic amine group. Due to the abundance of data, allosteric D₂ R ligands and D₂ R modulators from patents are not discussed in this review.

The crystal structures, Hirshfeld surface analyses and energy frameworks of 8-{1-[3-(cyclo-pent-1-en-1-yl)benz-yl]piperidin-4-yl}-2-meth-oxy-quinoline and 8-{4-[3-(cyclo-pent-1-en-1-yl)benz-yl]piperazin-1-yl}-2-meth-oxy-quinoline

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.

Crystal structure and Hirshfeld surface analysis of the hydro-chloride salt of 8-{4-[(6-phenyl-pyridin-3-yl)meth-yl]piperazin-1-yl}-3,4-di-hydro-quinolin-2(1H)-one

The amine 8-{4-[(6-phenyl-pyridin-3-yl)meth-yl]piperazin-1-yl}-3,4-di-hydro-quinolin-2(1H)-one was crystallized as the hydro-chloride salt, 4-(2-oxo-1,2,3,4-tetra-hydro-quinolin-8-yl)-1-[(6-phenyl-pyridin-3-yl)meth-yl]piperazin-1-ium chloride, C25H27N4 +·Cl- (I·HCl). The conformation of the organic cation is half-moon in shape enclosing the chloride anion. The piperidine ring of the 3,4-di-hydro-quinolin-2(1H)-one moiety has a screw-boat conformation, while the piperazine ring has a chair conformation. In the biaryl group, the pyridine ring is inclined to the phenyl ring by 40.17 (7) and by 36.86 (8)° to the aromatic ring of the quinoline moiety. In the crystal, the cations are linked by pairwise N-H⋯O hydrogen bonds, forming inversion dimers enclosing an R 2 2(8) ring motif. The Cl- anion is linked to the cation by an N-H⋯Cl hydrogen bond. These units are linked by a series of C-H⋯O, C-H⋯N and C-H⋯Cl hydrogen bonds, forming layers lying parallel to the ab plane.

Catalytic Oxidative Carbonylation of Amino Moieties to Ureas, Oxamides, 2-Oxazolidinones, and Benzoxazolones

The direct syntheses of ureas, oxamides, 2-oxazolidinones, and benzoxazolones by the oxidative carbonylation of amines, β-amino alcohols, and 2-aminophenols allows us to obtain high value added molecules, which have a large number of important applications in several fields, from very simple building blocks. We have found that it is possible to perform these transformations using the PdI2 /KI catalytic system in an ionic liquid, such as 1-butyl-3-methylimidazolium tetrafluoroborate, as the solvent, the solvent/catalyst system can be recycled several times with only a slight loss of activity, and the product can be recovered easily by crystallization.