FeCl3–SiO2 promoted one-pot, three-component synthesis of novel 1,5-benzodiazepine derivatives

Ferrocene anchored activated carbon as a versatile catalyst for the synthesis of 1,5-benzodiazepines via one-pot environmentally benign conditions

1,5-Benzodiazepine is considered as one of the central moieties in the core unit of most drug molecules. Construction of such moieties with a new C–N bond under solvent-free and mild reaction conditions is challenging. Herein, we present a benign protocol for one pot synthesis of 1,5-benzodiazepine derivatives by using ferrocene (FC) supported activated carbon (AC) as a heterogeneous catalyst. The catalyst FC/AC was characterized by several analytical and spectroscopic techniques to reveal its physicochemical properties and for structural confirmation. The synthesized catalyst FC/AC was explored for its catalytic activity in the synthesis of 1,5-benzodiazepines through condensation of o-phenylenediamine (OPDA) and ketones (aromatic and aliphatic) under solvent-free conditions. The robust 10 wt% FC/AC catalyst demonstrated appreciable activity with 99% conversion of diamines and 91% selectivity towards the synthesis of the desired benzodiazepine derivatives under solvent-free conditions at 90 °C in 8 h. Additionally, several reaction parameters such as catalyst loading, reaction temperature, effect of reaction time and effect of different solvents on selectivity were also studied and discussed in-depth. To understand the scope of the reaction, several symmetrical and unsymmetrical ketones along with different substituted diamines were tested with the synthesized catalyst. All prepared reaction products were obtained in good to efficient yields and were isolated and identified as 1,5-benzodiazepines and no side products were observed. The obtained catalyst characterization data and the activity studies suggested that, the synergetic effect occurred due to the uniform dispersion of ferrocene over the AC surface with numerous acidic sites which triggered the reaction of diamine and ketone to form the corresponding benzodiazepine derivative and the same was illustrated in the plausible mechanism. Furthermore, the synthesized catalyst was tested for leaching and recyclability, and the results confirmed that catalyst can be used for up to six consecutive cycles without much loss in the catalytic activity and its morphology which makes the process sustainable and economical for scale-up production. The present method offered several advantages such as an ecofriendly method, excellent yields, sustainable catalytic transformation, easy work-up and isolation of products, and quick recovery of catalyst.

1,5-Benzodiazepine is considered as one of the central moieties in the core unit of most drug molecules.

Assessment of elementary derivatives of 1,5-benzodiazepine as anticancer agents with synergy potential

Herein, we designed and synthesized 1,5-benzodiazepines as a lead molecule for anticancer activity and as potent synergistic activity with drug Methotrexate. Working under the framework of green chemistry principles, series of 1,5-benzodiazepine derivatives (3a-3a¹) were synthesized using biocatalyst i.e. thiamine hydrochloride under solvent free neat heat conditions. These compounds were screened for in vitro anti cancer activity against couple of cancer cell lines (HeLa and HEPG2) and normal human cell line HEK-293 via MTT assay. The IC₅₀ values for the compounds were in the range 0.067 to 0.35 µM, better than Paclitaxel and compatible with the drug Methotrexate. Compound 3x was found to be influential against both the cell lines with IC₅₀ values of 0.067 ± 0.002 µM against HeLa and 0.087 ± 0.003 µM against HEPG2 cell line, having activity as compatible to the standard drug Methotrexate. Bioinformatic analysis showed that these compounds are good tyrosine kinase inhibitors which was then proved using enzyme inhibition assay. The studies of apoptosis revealed late apoptotic mode of cell death for the compounds against HEPG2 cancer cell line using flow cytometry method. Synergistic studies of compound 3x and drug Methotrexate showed that the combination was highly active against cancer HeLa and HEPG2 cell line with IC50 value 0.046 ± 0.002 µM and 0.057 ± 0.002 µM respectively, which was well supported by apoptosis pathway. Further the compounds proved its scope as DNA intercalating agents, as its molecular docking and DNA binding studies revealed that the compounds would fit well into the DNA strands.

Multicomponent reactions as a potent tool for the synthesis of benzodiazepines

Benzodiazepines (BZDs), a diverse class of benzofused seven-membered N-heterocycles, display essential pharmacological properties and play vital roles in some biochemical processes. They have mainly been prescribed as potential therapeutic agents, which interestingly represent various biological activities such as anticancer, anxiolytic, antipsychotic, anticonvulsant, antituberculosis, muscle relaxant, and antimicrobial activities. The extensive biological activities of BZDs in various fields have encouraged medicinal chemists to discover and design novel BZD-based scaffolds as potential therapeutic candidates with the favorite biological activity through an efficient protocol. Although certainly valuable and important, conventional synthetic routes to these bicyclic benzene compounds contain methodologies often requiring multistep procedures, which suffer from waste materials generation and lack of sustainability. By contrast, multicomponent reactions (MCRs) have recently advanced as a green synthetic strategy for synthesizing BZDs with the desired scope. In this regard, MCRs, especially Ugi and Ugi-type reactions, efficiently and conveniently supply various complex synthons, which can easily be converted to the BZDs via suitable post-transformations. Also, MCRs, especially Mannich-type reactions, provide speedy and economic approaches for the one-pot and one-step synthesis of BZDs. As a result, various functionalized-BZDs have been achieved by developing mild, efficient, and high-yielding MCR protocols. This review covers all aspects of the synthesis of BZDs with a particular focus on the MCRs as well as the mechanism chemistry of synthetic protocols. The present manuscript opens a new avenue for organic, medicinal, and industrial chemists to design safe, environmentally benign, and economical methods for the synthesis of new and known BZDs.

Synthesis and catalytic evaluation of PVP-CeO2/rGO as a highly efficient and recyclable heterogeneous catalyst for multicomponent reactions in water

A highly efficient and eco-friendly route for the reduction of graphene oxide (GO) to reduced graphene oxide (rGO) was developed by using polyvinylpyrrolidone coated CeO₂ NPs (PVP-CeO₂) as a reducing and stabilizing agent. The resulting carbonaceous material, PVP-CeO₂/rGO, was well characterized with different spectroscopic techniques such as Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), elemental mapping, Transmission Electron Microscopy (TEM), Raman spectroscopy, powder X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), X-ray Photoelectron Spectroscopy (XPS), and Thermal Gravimetric (TG) analyses. The material exhibited high catalytic potential towards multicomponent reactions for the synthesis of biologically relevant benzodiazepine derivatives in aqueous media. The efficiency of the material for the desired reaction was shown in the form of an excellent product yield (96-98%) and a very short reaction time period (7-10 min). The use of water as solvent and recyclability of the catalyst made the present protocol acceptable from a green perspective.