1,4-Benzodiazepin-2-ones in medicinal chemistry

Rh(III) Catalyzed Redox-Neutral C-H Activation/[5 + 2] Annulation of Aroyl Hydrazides and Sulfoxonium Ylides: Synthesis of Benzodiazepinones

We herein report the Rh(III) catalyzed redox-neutral C-H activation/[5 + 2] annulation of aroyl hydrazides with sulfoxonium ylides as safe carbene precursors. The reaction shows excellent functional group tolerance, broad substrate scope, and scalability. We demonstrated the synthetic utility of the protocol via the synthesis of various diazepam drug analogues, late-stage functionalization of probenecid drug, and large scale synthesis. Finally, kinetic studies revealed C-H activation as the rate-determining step.

Urotensin II Receptor Modulation with 1,3,4-Benzotriazepin-2-one Tetrapeptide Mimics

Urotensin II receptor (UT) modulators that differentiate the effects of the endogenous cyclic peptide ligands urotensin II (UII) and urotensin II-related peptide (URP) offer potential for dissecting their respective biological roles in disease etiology. Selective modulators of hUII and URP activities were obtained using 1,3,4-benzotriazepin-2-one mimics of a purported bioactive γ-turn conformation about the Bip-Lys-Tyr tripeptide sequence of urocontrin ([Bip4]URP). Considering an active β-turn conformer about the shared Phe-Trp-Lys-Tyr sequence of UII and URP, 8-substituted 1,3,4-benzotriazepin-2-ones were designed to mimic the Phe-Bip-Lys-Tyr tetrapeptide sequence of urocontrin, synthesized, and examined for biological activity. Subtle 5- and 8-position modifications resulted in biased signaling and selective modulation of hUII- or URP-induced vasoconstriction. For example, p-hydroxyphenethyl analogs 17b-d were strong Gα13 and βarr1 activators devoid of Gαq-mediated signaling. Tertiary amides 15d and 17d negatively modulated hUII-induced vasoconstriction without affecting URP-mediated responses. Benzotriazepinone carboxamides proved to be exceptional tools for elucidating the pharmacological complexity of UT.

Synthesis of 4-Aryl-1,3,4-benzotriazepinones from Isatoic Anhydrides and Hydrazonyl Chlorides

An efficient synthesis of 4-aryl-1,3,4-benzotriazepinones from readily available isatoic anhydrides and hydrazonyl chlorides was developed. In this facile protocol, a series of functionalized 1,3,4-benzotriazepinones were conveniently obtained with broad substrate scope and excellent functional group tolerance.

Dimeric Benzodiazepines as Peptide Mimetics to Overcome p53-Dependent Drug Resistance of Tumors

Benzodiazepines that consist of one α- and one β-amino acid residues linked together in a seven-membered heterocyclic ring could be treated as small, rigid, cyclic dipeptides capable of exhibiting a wide range of biological activities. During our research on novel analogues of anthramycin, a tricyclic antibiotic benzodiazepine, we developed the synthesis of two benzodiazepine dimers, obtained through the cyclization of appropriate linear tripeptides. The synthesized compounds were tested on a panel of seven cancer and normal cell lines. The developed molecules exhibited promising cytotoxic activity against the lung cancer cell lines A549 and NCI-H1299 and the epidermoid carcinoma cell line A-431. Moreover, they showed significant selectivity compared to the reference cell lines (BJ-human normal skin fibroblasts and MRC-5-human normal lung cell line). When tested on two isogenic cell lines, HCT116 and HCT116p53^-/- (colon cancer), contrary to cisplatin being used as a positive control, the obtained compounds showed a cytotoxic effect independent of the p53 protein status. For the above reasons, the obtained compounds can be considered a new group of promising anticancer agents, useful in the fight against p53-dependent drug resistance in cancers. They can also be treated as convenient, leading structures suitable for further optimization and searching for more active and selective molecules.

First evaluation of the anxiolytic-like effects of a bromazepam‑palladium complex in mice

A significant fraction of patients are affected by persistent fear and anxiety. Currently, there are several anxiolytic drug options, however their clinical outcomes do not fully manage the symptoms. Here, we evaluated the effects of a bromazepam‑palladium derivative [2-{(7-bromo-2-oxo-1,3-dihydro-2H-1,4-benzodiazepin-5-il)pyridinyl-κ²-N,N}chloropalladium(II)], [(BMZ)PdCl₂], on fear/anxiety and memory-related behavior in mice. For this, female Swiss mice were treated intraperitoneally (i.p.) with saline (NaCl 0.9%) or [(BMZ)PdCl₂] (0.5, 5.0, or 50 μg/kg). After 30 min, different tests were performed to evaluate anxiety, locomotion, and memory. We also evaluated the acute toxicity of [(BMZ)PdCl₂] using a cell viability assay (neutral red uptake assay), and whether the drugs mechanism of action involves the γ-aminobutyric acid type A (GABA_A) receptor complex by pre-treating animals with flumazenil (1.0 mg/kg, i.p., a competitive antagonist of GABA_A-binding site). Our results demonstrate that [(BMZ)PdCl₂] induces an anxiolytic-like phenotype in the elevated plus-maze test and that this effect can be blocked by flumazenil. Furthermore, there were no behavioral alterations induced by [(BMZ)PdCl₂], as evaluated in the light-dark box, open field, and step-down passive avoidance tests. In the acute toxicity assay, [(BMZ)PdCl₂] presented IC₅₀ and LD₅₀ values of 218 ± 60 μg/mL and 780 ± 80 mg/kg, respectively, and GSH category 4. Taken together, our results show that the anxiolytic-like effect of acute treatment with [(BMZ)PdCl₂] occurs through the modulation of the benzodiazepine site in the GABA_A receptor complex. Moreover, we show indications that [(BMZ)PdCl₂] does not promote sedation and amnesia and presents the same toxicity as the bromazepam prototype.

Palladium-catalyzed native α-amino acid derivative-directed arylation/oxidation of benzylic C-H bonds: synthesis of 5-aryl-1,4-benzodiazepin-2-ones

A Pd-catalyzed, native α-amino acid derivative-directed benzylic C-H bond arylation/oxidation with aryl iodides was developed. The natural amino acid auxiliary could serve as a desired building block for formation of 5-aryl-1,4-benzodiazepin-2-ones after removal of the trifluoroacetyl protecting group. The bifunctional reaction probably proceeded through a sequential benzylic arylation/oxidation process.

A Convenient, Rapid, Conventional Heating Route to MIDA Boronates

A cheap, conventional, sealed heating reactor proved to be a useful alternative to a microwave reactor in the synthesis of a >20-member MIDA boronate library (MIDA = N-methyliminodiacetic acid). Reaction times were 10 min and work-ups were minimal, saving on energy and solvent usage.

Benzodiazepines: Drugs with Chemical Skeletons Suitable for the Preparation of Metallacycles with Potential Pharmacological Activity

The synthesis of organometallic compounds with potential pharmacological activity has attracted the attention of many research groups, aiming to take advantage of aspects that the presence of the metal-carbon bond can bring to the design of new pharmaceutical drugs. In this context, we have gathered studies reported in the literature in which psychoactive benzodiazepine drugs were used as ligands in the preparation of organometallic and metal complexes and provide details on some of their biological effects. We also highlight that most commonly known benzodiazepine-based drugs display molecular features that allow the preparation of metallacycles via C-H activation. These organometallic compounds merit further attention regarding their potential biological effects, not only in terms of psychoactive drugs but also in the search for drug replacements, for example, for cancer treatments.

Synthesis of Benzodiazepines Through Ring Opening/Ring Closure of Benzimidazole Salts

Pyrido-benzodiazepine derivatives are undoubtedly one of the most important structural motifs in the marketed drugs and the drug candidates. Commonly synthetic methods for construction of the benzodiazepine ring derivatives are based on the condensation reactions of two highly functionalized synthons. The development of synthesis for these compounds, however, is hampered by the regioselectivity and atom economy. In this work, a one-step synthesis of pyrido-benzodiazepine backbones and its analogues is achieved through continuous ring-opening hydrolysis of benzimidazole salts and intramolecular C-H bond activation. The reaction mechanism is explored by control experiments and density functional theory (DFT) calculations.

Two decades of recent advances of Ugi reactions: synthetic and pharmaceutical applications

Multicomponent reactions (MCRs) are powerful synthetic tools in which more than two starting materials couple with each other to form multi-functionalized compounds in a one-pot process, the so-called “tandem”, “domino” or “cascade” reaction, or utilizing an additional step without changing the solvent, the so-called a sequential-addition procedure, to limit the number of synthetic steps, while increasing the complexity and the molecular diversity, which are highly step-economical reactions. The Ugi reaction, one of the most common multicomponent reactions, has recently fascinated chemists with the high diversity brought by its four- or three-component-based isonitrile. The Ugi reaction has been introduced in organic synthesis as a novel, efficient and useful tool for the preparation of libraries of multifunctional peptides, natural products, and heterocyclic compounds with stereochemistry control. In this review, we highlight the recent advances of the Ugi reaction in the last two decades from 2000–2019, mainly in the synthesis of linear or cyclic peptides, heterocyclic compounds with versatile ring sizes, and natural products, as well as the enantioselective Ugi reactions. Meanwhile, the applications of these compounds in pharmaceutical trials are also discussed.

We highlight the recent advances of the Ugi reaction in the last two decades from 2000–2019, mainly in the synthesis of linear or cyclic peptides, heterocyclic compounds with versatile ring sizes, and natural products, as well as the enantioselective Ugi reactions.

New pyrazolyl-dibenzo[b,e][1,4]diazepinones: room temperature one-pot synthesis and biological evaluation

Several new (5-aryloxy-pyrazolyl)- and (5-aryl/olefin-sulfanyl-pyrazolyl)-dibenzo[b,e] [1,4] diazepinone scaffolds have been synthesized, by assembling 5-substituted 3-methyl-1-phenyl-pyrazole-4-carbaldehydes of varied nature with different cyclic diketones and aromatic diamines successfully in the presence of indium chloride in acetonitrile, at room temperature. Desired products are excellent in the purity and isolated without chromatography. All new structures are confirmed, on the basis of single-crystal X-ray diffraction data of representative 29e. Compounds reported in the present work revealed good antioxidant, antimicrobial and antiproliferative activities with promising FRAP (ferric reducing antioxidant power), bacterial resistance and human solid tumor cell growth inhibitory values, respectively. Compounds 25c and 29e, overall, registered good to moderate activity against A549 (lung), HeLa (cervix), SW1573 (lung) T-47D (breast) and WiDr (colon) cell lines, with GI₅₀ values in the 2.6-5.1 μM and 1.8-7.5 μM ranges, respectively. Molecular docking was carried out to elucidate the binding modes of the compounds (25c, 29e) to topoisomerase I and II.

[3 + 2] Cycloaddition and Cascade Radical Reactions for the Synthesis of Trifluoromethylated Tetrahydrobenzodiazepin-3-ones

A reaction sequence involving three-component [3 + 2] cycloaddition of azomethine ylides followed by CuI-catalyzed cascade trifluoromethyl radical addition and cyclization is developed for diastereoselective synthesis of fused-tetrahydrobenzodiazepin-3-ones.

Structural Simplification of Natural Products

Natural products (NPs) are important sources of clinical drugs due to their structural diversity and biological prevalidation. However, the structural complexity of NPs leads to synthetic difficulties, unfavorable pharmacokinetic profiles, and poor drug-likeness. Structural simplification by truncating unnecessary substructures is a powerful strategy for overcoming these limitations and improving the efficiency and success rate of NP-based drug development. Herein, we will provide a comprehensive review of the structural simplification of NPs with a focus on design strategies, case studies, and new technologies. In particular, a number of successful examples leading to marketed drugs or drug candidates will be discussed in detail to illustrate how structural simplification is applied in lead optimization of NPs.

Synthesis of new tricyclic 5,6-dihydro-4H-benzo[b][1,2,4]triazolo[1,5-d][1,4]diazepine derivatives by [3+ + 2]-cycloaddition/rearrangement reactions

Two new series of tricyclic heterocycles, namely 5,6-dihydro-4H-benzo[b][1,2,4]triazolo[1,5-d][1,4]diazepinium salts 10 and the related neutral, free bases 13 were synthesized from 4-acetoxy-1-acetyl-4-phenylazo-1,2,3,4-tetrahydroquinolines 8 and nitriles 9 in the presence of aluminium chloride by the [3⁺ + 2]-cycloaddition reaction of the in situ generated azocarbenium intermediates 14 followed by a ring-expansion rearrangement. In the rearrangement reaction, the phenyl substituent in the initially formed spiro-triazolium adducts 16 underwent a [1,2]-migration from C(3) to the electron-deficient N(2). This led to the ring expansion from 6-membered piperidine to 7-membered diazepine furnishing the tricyclic 1,2,4-triazole-fused 1,4-benzodiazepines.

Gram-Scale Laboratory Synthesis of TC AC 28, a High-Affinity BET Bromodomain Ligand

TC AC 28, 6-(1H-Indol-4-yl)-8-methoxy-1-methyl-4H-[1,2,4]triazolo[4,3-a][1,4]benzodiazepine-4-acetic acid methyl ester, has been synthesized on a near-gram scale in seven steps with notable improvements in the reported poor-yielding last two steps enabling this key chemical probe compound to be available for researchers.

An Atom-Economical Method To Prepare Enantiopure Benzodiazepines with N-Carboxyanhydrides

The development of a rapid, one-pot synthesis of diazepinones with simple reagents is described. N-Carboxyanhydrides (NCAs) are employed as amino acid building blocks that react with o-ketoanilines sequentially as electrophiles and nucleophiles to form diazepinones with water and carbon dioxide as byproducts. Notably, these reactions enable the coupling of stereodefined amino acid derived NCAs without racemization. This method is demonstrated by an improved synthesis of a key intermediate toward a bromodomain and extra-terminal (BET) bromodomain inihibitor.

Interactions between 2,4-bis-pteridine-1,5-benzodiazepine and group 12 dihalides: synthesis, spectral and XRD structural studies and theoretical calculations

2,4-Bis(1,3,7-trimethyl-pteridine-2,4(1H,3H)-dione-6-yl)-2,3-dihydro-2-methyl-1H-1,5-benzodiazepine (DLMBZD) has been prepared and its molecular and crystal structures have been determined from spectral and XRD data. The benzodiazepine ligand was reacted with zinc(ii), cadmium(ii) and mercury(ii) chloride, bromide and iodide to give complexes with general formula [M(DLMBZD)X₂]. The complexes have been synthesized and characterized by IR, NMR and elemental analysis. The structure of seven complexes has been obtained by single crystal X-ray diffraction. In all the cases, the metal is (2 + 2 + 1)-five-coordinated by two halide ligands, two nitrogen atoms from pyrazine and diazepine rings and a carbonyl oxygen from a pteridine ring. The coordinated-metal environment is a square-based pyramid, with increasing trigonality from Hg(ii) to Zn(ii) complexes. To coordinate the metals, the ligand folds itself, establishing four intramolecular σ-π interactions with the pyrimidine and pyrazine rings. A topological analysis of the electron density using the Quantum Theory of Atoms in Molecules and the complexes stability has been performed.

A facile and chemoselective synthesis of 1,4-benzodiazepin-2-ones and dienyl thiazolidin-4-ones

A chemoselective synthesis of novel 1,4-benzodiazepin-2-ones and dienyl thiazolidin-4-one carboxylates in excellent yields by ring transformation reactions of functionally decorated 2-azetidin-3-thiazolidin-4-ones is reported.

Palladium-benzodiazepine derivatives as promising metallodrugs for the development of antiepileptic therapies

We synthesized two organometallic diazepam-palladium(II) derivatives by C-H activation of diazepam (DZP) with palladium salts, i.e., PdCl2 and Pd(OAc)2 (OAc=acetate). Both compounds obtained are air stable and were isolated in good yields. The anticonvulsant potential of the complexes, labeled [(DZP)PdCl]2 and [(DZP)PdOAc]2, was evaluated through two animal models: pentylenetetrazole (PTZ)- and picrotoxin (PTX)-induced convulsions. The organometallic DZP-palladium(II) acetate complex, [(DZP)PdOAc]2, significantly increased (p<0.01 or p<0.001) latencies and protected the animals against convulsions induced by PTZ and PTX, while the analogous chloro derivative, [(DZP)PdCl]2, was effective (p<0.01) only in the PTZ model. These effects appear to be mediated through the GABAergic system. The possible mechanism of action of the DZP-palladium(II) complexes was also confirmed with the use of flumazenil (FLU), a GABAA-benzodiazepine receptor complex site antagonist. Herein, we present the first report of the anticonvulsant properties of organometallic DZP-palladium(II) complexes as well as evidence that these compounds may play an important role in the study of new drugs to treat patients with epilepsy.

Multicomponent synthesis of diverse 1,4-benzodiazepine scaffolds

The 1,4-benzodiazepine (BDZ) scaffold is of particular interest in drug design due to a balanced ensemble of beneficial physicochemical properties including a semirigid and compact diazepine ring with spatial placements of several substituents, combined with low number of rotatable bonds, hydrogen bond donors and acceptors, and intermediate lipophilicity. As an alternative to traditional multistep sequential syntheses, we designed routes employing one-pot MCRs to accelerate access diverse BDZ scaffolds in two or three steps.

Exploiting the acylating nature of the imide-Ugi intermediate: a straightforward synthesis of tetrahydro-1,4-benzodiazepin-2-ones

We describe a simple and novel protocol for the synthesis of tetrahydro-1,4-benzodiazepin-2-ones with three points of diversity, exploiting the acylating properties of the recently rediscovered Ugi-imide. The final compounds can be easily prepared in three synthetic steps using a multicomponent reaction, a Staudinger reduction, and an acylative protocol, with good to excellent yields for each synthetic step.

Synthesis and biological evaluation of 1,4-benzodiazepin-2-ones with antitrypanosomal activity

A library of 1,4-benzodiazepines has been synthesized and evaluated against Trypanosoma brucei, a causative parasite of Human African trypanosomiasis. Benzodiazepines possessing a P2- transporter motif were found to have MIC values as low as 0.78 μM.