Modification of the clozapine structure by parallel synthesis

Mn(III)-Mediated Radical Addition/Cyclization of Isocyanides with Aryl Boronic Acids/Diarylphosphine Oxides: Access to 11-Functionalized Dibenzodiazepines

A Mn(III)-mediated radical addition/cyclization reaction of isocyanides with aryl boronic acids/diarylphosphine oxides has been developed. A series of 11-arylated/-phosphorylated dibenzodiazepines were efficiently constructed in moderate to excellent yields under mild reaction conditions via imidoyl radical process. The present protocol offers novel access to functionalized seven-membered N-heterocycles.

Palladium-Catalyzed Benzodiazepines Synthesis

This review is focused on palladium-catalyzed reactions as efficient strategies aimed at the synthesis of different classes of benzodiazepines. Several reaction typologies are reported including hydroamination, amination, C–H arylation, N-arylation, and the Buchwald–Hartwig reaction, depending on the different substrates identified as halogenated starting materials (activated substrates) or unactivated unsaturated systems, which then exploit Pd(0)- or Pd(II)-catalytic species. In particular, the use of the domino reactions, as intra- or intermolecular processes, are reported as an efficient and eco-compatible tool to obtain differently functionalized benzodiazepines. Different domino reaction typologies are the carboamination, aminoarylation, aminoacethoxylation, aminohalogenation, and aminoazidation.

Simplified Procedure for General Synthesis of Monosubstituted Piperazines-From a Batch Reaction Vessel to a Flow (Microwave) Reactor

We reported a novel simplified synthetic procedure for the preparation of monosubstituted piperazine derivatives which can now be easily prepared in a one-pot-one-step way from a protonated piperazine with no need of introduction of a protecting group. Reactions, proceeding either at room or higher temperatures in common solvents, involve heterogeneous catalysis by metal ions supported on commercial polymeric resins. A general synthetic scheme was successfully applied to afford a wide range of monosubstituted piperazines. Furthermore, we picked up a set of piperazine derivatives and studied the possibilities of microwave acceleration of given synthetic reactions to make them even more efficient. Our research proceeded from a simple batch technique to the construction of a flow microwave reactor prototype and resulted in promising findings which are summarized and discussed in the article.

The dopamine D2 receptor dimer and its interaction with homobivalent antagonists: homology modeling, docking and molecular dynamics

In order to apply structure-based drug design techniques to G protein-coupled receptor complexes, it is essential to model their 3D structure and to identify regions that are suitable for selective drug binding. For this purpose, we have developed and tested a multi-component protocol to model the inactive conformation of the dopamine D2 receptor dimer, suitable for interaction with homobivalent antagonists. Our approach was based on protein-protein docking, applying the Rosetta software to obtain populations of dimers as present in membranes with all the main possible interfaces. Consensus scoring based on the values and frequencies of best interfaces regarding four scoring parameters, Rosetta interface score, interface area, free energy of binding and energy of hydrogen bond interactions indicated that the best scored dimer model possesses a TM4-TM5-TM7-TM1 interface, which is in agreement with experimental data. This model was used to study interactions of the previously published dopamine D2 receptor homobivalent antagonists based on clozapine,1,4-disubstituted aromatic piperidines/piperazines and arylamidoalkyl substituted phenylpiperazine pharmacophores. It was found that the homobivalent antagonists stabilize the receptor-inactive conformation by maintaining the ionic lock interaction, and change the dimer interface by disrupting a set of hydrogen bonds and maintaining water- and ligand-mediated hydrogen bonds in the extracellular and intracellular part of the interface. Graphical Abstract Structure of the final model of the dopamine D2 receptor homodimer, indicating the distancebetween Tyr37 and Tyr 5.42 in the apo form (left) and in the complex with the ligand (right).

Piperazine scaffold: A remarkable tool in generation of diverse pharmacological agents

Piperazine is one of the most sought heterocyclics for the development of new drug candidates. This ring can be traced in a number of well established, commercially available drugs. Wide array of pharmacological activities exhibited by piperazine derivatives have made them indispensable anchors for the development of novel therapeutic agents. The review herein highlights the therapeutic significance of piperazine derivatives. Various therapeutically active piperazine derivatives developed by several chemists are reported here.

A catalytic route to dibenzodiazepines involving Buchwald–Hartwig coupling: reaction scope and mechanistic consideration

We report a new synthetic method for the synthesis of a family of dibenzodiazepines (DBDAs), employing Pd-catalyzed C–N coupling of o-bromoaldimine, with o-bromoaniline as the key step.

MoO2Cl2(DMF)2 catalyzed microwave assisted reductive cyclisation of nitroaromatics into dibenzodiazepines

Microwave induced, MoO₂Cl₂(DMF)₂ catalyzed synthesis of novel dibenzodiazepine scaffolds with potential biocidal activity.

Copper(ii)-catalyzed coupling reaction: an efficient and regioselective approach to N′,N′-diaryl acylhydrazines

An efficient and regioselective copper(ii)-catalyzed coupling reaction of N′-aryl acylhydrazines for the synthesis of N′,N′-diaryl acylhydrazines has been developed.

Complexation, thermal and catalytic studies of N-substituted piperazine, morpholine and thiomorpholine with some metal ions

Several Cu(II), Pt(II) and Ni(II) complexes of N-substituted, piperazine (NN donor), morpholine (NO donor) and thiomorpholine (NS donor) derivatives were synthesized and their thermal behavior and catalytic activity in epoxidation reaction of cis-diphenylethylene were studied using oxygen sources NaOCl. The coordination compounds of Cu(II), Pt(II) and Ni(II) having general formula [MLCl]Cl, [ML2l]Cl2 or [ML]Cl2 with tetra coordinated geometry around metal ions have been isolated as solid. All the ligands and complexes were identified by spectroscopic methods and elemental analysis, magnetic measurements, electrical conductance and thermal analysis. A square planer structures have been proposed for all complexes. The thermal stability of the complexes discussed in terms of ligands donor atoms, geometry and central metal ions. The complexes have a similar thermal behavior for the selected metal ions. The thermogravimetric analyses suggest high thermal stability for most complexes followed by thermal decomposition in different steps. The decomposition processes were observed as water elimination, chloride anion removal and degradation of the organic ligands. Catalytic ability of the complexes were examined and found that all the complexes can effectively catalyze the epoxidation of cis-stilbene with NaOCl.

Assessment of possible immunotoxicity of the antipsychotic drug clozapine

OBJECTIVES

The immunomodulatory effects of clozapine (CLZ), antipsychotic drug, were investigated in vivo using female Balb/c mice. The main aim of this study was to evaluate the immunomodulatory effects of CLZ, antipsychotic drug, following daily intraperitoneal injection to female Balb/c mice over a period of 21 days.

METHODS

Mice were divided into five groups, eight animals per group. Group I, served as a control group, received only the vehicle. Groups II-V received a daily intraperitoneal dose of CLZ (1, 5, 10 and 20 mg/kg, respectively) over a period of 21 days.

KEY FINDINGS

CLZ has shown a significant decrease in the animal body weight, and it showed a significant decrease in the percentage of circulating neutrophils and lymphocytes while circulating monocytes were increased. The immunotoxicity has been also assessed by evaluating spleen cellularity, humoral immune response to a foreign antigen using sheep red blood cells and delayed-type hypersensitivity reaction. The results showed a marked suppression in these responses in CLZ-treated mice compared with the control group. Detectable changes have also been noticed in the histology of the footpad tissue and spleen.

CONCLUSIONS

Results showed significant immunomodulatory effects of CLZ when used in Balb/c mice.

Homobivalent ligands of the atypical antipsychotic clozapine: design, synthesis, and pharmacological evaluation

To date all typical and atypical antipsychotics target the dopamine D(2) receptor. Clozapine represents the best-characterized atypical antipsychotic, although it displays only moderate (submicromolar) affinity for the dopamine D(2) receptor. Herein, we present the design, synthesis, and pharmacological evaluation of three series of homobivalent ligands of clozapine, differing in the length and nature of the spacer and the point of attachment to the pharmacophore. Attachment of the spacer at the N4' position of clozapine yielded a series of homobivalent ligands that displayed spacer-length-dependent gains in affinity and activity for the dopamine D(2) receptor. The 16 and 18 atom spacer bivalent ligands were the highlight compounds, displaying marked low nanomolar receptor binding affinity (1.41 and 1.35 nM, respectively) and functional activity (23 and 44 nM), which correspond to significant gains in affinity (75- and 79-fold) and activity (9- and 5-fold) relative to the original pharmacophore, clozapine. As such these ligands represent useful tools with which to investigate dopamine receptor dimerization and the atypical nature of clozapine.

I2-mediated diversity oriented diastereoselective synthesis of amino acid derived trans-2,5-disubstituted morpholines, piperazines, and thiomorpholines

Diastereoselective trans-2,5-disubstituted amino acids derived diverse morpholines, piperazines and thiomorpholines were prepared in 30 min-1 h with high yields through iodine-mediated 6-exotrig type cyclization from a single common synthetic intermediate. The displacement of iodine with hydride ion gave a methyl substituent at the 2-position of morpholines which provides an additional opportunity for diversity oriented nucleophilic substitution on the rings as well as incorporation of substituents at the 5-position from amino acids constituents.

Concise palladium-catalyzed synthesis of dibenzodiazepines and structural analogues

A general and highly efficient protocol for the synthesis of dibenzodiazepines and their structural analogues is reported. In the presence of catalytic quantities of palladium, readily accessible precursors are cross-coupled with ammonia and then spontaneously undergo an intramolecular condensation to form the corresponding dibenzodiazepines in one step. This new strategy is applicable to the construction of a wide variety of dibenzooxazepines and other structurally related heterocycles.

Synthesis of difluoroaryldioxoles using BrF3

A novel synthesis of different aromatic and heteroaromatic difluorodioxole derivatives has been developed. The starting materials were catechols, which, after treatment with thiophosgene, formed at 0 °C the respective thiodioxoles. The latter were reacted for a short time with commercially available bromine trifluoride, producing potentially biologically important difluoroaryldioxoles in moderate to high yields.

Exploring structure-selectivity relationships of biogenic amine GPCR antagonists using similarity searching and dynamic compound mapping

We design and analyze compound selectivity sets of antagonists with differential selectivity against seven biogenic amine G-protein coupled receptors. The selectivity sets consist of a total of 267 antagonists and contain a spectrum of in part closely related molecular scaffolds. Each set represents a different selectivity profile. Using these com- pound sets, a systematic computational analysis of structure-selectivity relationships is carried out with different 2D similarity methods including fingerprints, recursive partitioning, clustering, and dynamic compound mapping. Screening calculations are performed in a background database containing nearly four million molecules. Fingerprint searching and compound mapping are found to enrich target-selective antagonists over family-selective ones. Dynamic compound mapping effectively discriminates database compounds from GPCR antagonists and consistently retains target-selective antagonists during the final dimension extension levels. Furthermore, the widely used MACCS key fingerprint displays a strong tendency to distinguish between target- and family-selective GPCR antagonists. Taken together, the results indicate that different types of 2D similarity methods are capable of distinguishing closely related molecules having different selectivity. The reported compound benchmark system is made freely available in order to enable selectivity-oriented analyses using other computational approaches.