Microwave-Assisted Solvent-Free Synthesis of Bis(dihydropyrimidinone)benzenes and Evaluation of their Cytotoxic Activity

Synthesis of 3,4-Dihydropyrimidin(thio)one Containing Scaffold: Biginelli-like Reactions

The interest in 3,4-dihydropyrimidine-2(1H)-(thio)ones is increasing every day, mainly due to their paramount biological relevance. The Biginelli reaction is the classical approach to reaching these scaffolds, although the product diversity suffers from some limitations. In order to overcome these restrictions, two main approaches have been devised. The first one involves the modification of the conventional components of the Biginelli reaction and the second one refers to the postmodification of the Biginelli products. Both strategies have been extensively revised in this manuscript. Regarding the first one, initially, the modification of one of the components was covered. Although examples of modifications of the three of them were described, by far the modification of the keto ester counterpart was the most popular approach, and a wide variety of different enolizable carbonylic compounds were used; moreover, changes in two or the three components were also described, broadening the substitution of the final dihydropyrimidines. Together with these modifications, the use of Biginelli adducts as a starting point for further modification was also a very useful strategy to decorate the final heterocyclic structure.

Tungsten-substituted molybdophosphoric acid impregnated with kaolin: effective catalysts for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones via biginelli reaction

A series of highly reusable heterogeneous catalysts (10-25 wt% PMo7W5/kaolin), consisting of tungsten-substituted molybdophosphoric acid, H3PMo7W5O40·24H2O (PMo7W5) impregnated with acid treated kaolin clay was synthesized by the wetness impregnation method. The newly synthesized catalyst was fully characterized using inductively coupled plasma-atomic emission spectroscopy (ICP-AES), Fourier transform infrared (FT-IR), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) analysis and thermal analysis (TG-DTA). The synthesized materials were shown to be efficient in the synthesis of 3,4-dihydropyrimidin-2(1H)-ones via Biginelli reaction under solvent-free conditions. The obtained results indicate that 20% PMo7W5/kaolin catalyst showed remarkably enhanced catalytic activity compared to the bulk PMo7W5 catalyst, and also the (10 and 15%) PMo7W5 catalyst supported on kaolin clay.

Biological activity of dihydropyrimidinone (DHPM) derivatives: A systematic review

Dihydropyrimidinones are heterocycles with a pyrimidine moiety in the ring nucleus, which, in recent decades, have aroused interest in medicinal chemistry due to alleged versatile biological activity. In this systematic review, we describe the currently published activities of dihydropyrimidinone derivatives. Between 1990 and December 31st, 2016, 115 articles outlined biological activities or toxicity of DHPM derivatives, 12 of those involved in vivo experiments. The main activities associated with this class of compounds are antitumoral (43 articles), anti-inflammatory (12 articles), antibacterial (20 articles) and calcium channel antagonism/inhibition (14 articles). Antitumoral activity is the main biological property evaluated, since the main representative compound of this class (monastrol) is a known Eg5 kinesin inhibitor. This review depicts a variety of other pharmacological activities associated with DHPM derivatives, but the main findings are essentially in vitro characteristics of the substances. This review presents the current state of the art of DHPM biological activities and demonstrates that there is still a need for further in vivo studies to better delineate the pharmacological potential of this class of substances.

Novel hybrid DHPM-fatty acids: synthesis and activity against glioma cell growth in vitro

We described the first synthesis of fatty acid 3,4-dihydropyrimidinones (DHPM-fatty acids) using the Biginelli multicomponent reaction. Antiproliferative activity on two glioma cell lines (C6 rat and U-138-MG human) was also reported. The novel DHPM-fatty acids reduced glioma cell viability relative to temozolomide. Hybrid oxo-monastrol-palmitic acid was the most potent, reducing U-138-MG human cell viability by ca. 50% at 10 μM. In addition, the DHPM-fatty acids showed a large safety range to neural cells, represented by the organotypic hippocampal culture. These results suggest that the increased lipophilicity of DHPM-fatty acids offer a promising approach to overcoming resistance to chemotherapy and may play an important role in the development of new antitumor drugs.

Synthesis of tetrahydropyrimidin-2-ones via FeCl3 catalyzed one-pot domino reaction of amines, methyl propiolate, aromatic aldehydes, and urea

Polysubstituted 3-arylaminoacrylate and tetrahydropyrimidin-2-one derivatives could be selectively produced from the one-pot domino reaction of arylamines, methyl propiolate, aromatic aldehydes, and urea in ethanol in the presence of FeCl3 as catalyst. Under similar reactions secondary amines such as morpholine and piperidine predominately afford tetrahydropyrimidin-2-one derivatives in good yields.

Novel 9-(alkylthio)-Acenaphtho[1,2-e]-1,2,4-triazine derivatives: synthesis, cytotoxic activity and molecular docking studies on B-cell lymphoma 2 (Bcl-2)

Background and purpose of the study

Acenaphtho derivatives have been reported as antitumor agents. Due to this fact and also with the aim of developing the chemistry of potentially bioactive heterocyclic compounds via efficient reactions, a facile procedure for the synthesis of 9-(alkylthio)-acenaphtho[1,2-e]-1,2,4-triazines via two step condensation of thiosemicarbazide and acenaphtylene-9,10-quinone to form acenaphtho[1,2-e]-1,2,4-triazine-9(8H)-thiones and subsequent reaction with benzyl chloride derivatives is reported.

Methods

9-(alkylthio) acenaphtho[1,2-e]-1,2,4-triazines were synthesized via the reaction of acenaphtho-9,10-quinone with thiosemicarbazide, and then with the benzyl chloride derivatives. Cytotoxicity of some prepared compounds was assessed through MTT assay on three different human cancerous cell lines (HL-60, MCF7, and MOLT-4 cells). Molecular docking studies were performed via AutoDock4.2 software in order to confirm an apoptosis-inducing activity of acenaphtho scaffolds via the Bcl-2 protein.

Results

Excellent yields of the products, short reaction times and simple work-up are attractive features of this synthetic protocol. The evaluated compounds exhibited moderate to good cytotoxic activities. Docking results on the active site of B-cell lymphoma 2 (Bcl-2) supported the experimental biological data and agreed well with previous in silico data for commonly used anti-cancer drugs. Moreover; results were analyzed considering binding efficiency indices.

Conclusions

The outcomes of the present study may be helpful in future targeting of Bcl-2 with the aim of developing apoptosis-inducing agents.

The Biginelli reaction with an imidazolium-tagged recyclable iron catalyst: kinetics, mechanism, and antitumoral activity

The present work describes the synthesis, characterization, and application of a new ion-tagged iron catalyst. The catalyst was employed in the Biginelli reaction with impressive performance. High yields have been achieved when the reaction was carried out in imidazolium-based ionic liquids (BMI⋅PF6, BMI⋅NTf2, and BMI⋅BF4), thus showing that the ionic-liquid effects play a role in the reaction. Moreover, the ion-tagged catalyst could be recovered and reused up to eight times without any noticeable loss in activity. Mechanistic studies performed by using high-resolution electrospray-ionization quadrupole-time-of-flight mass (HR-EI-QTOF) spectrometry and kinetic experiments indicate only one reaction pathway and rule out the other two possibilities under the development conditions. The theoretical calculations are in accordance with the proposed mechanism of action of the iron catalyst. Finally, the 37 dihydropyrimidinone derivatives, products of the Biginelli reaction, had their cytotoxicity evaluated in assays against MCF-7 cancer cell linages with encouraging results of some derivatives, which were virtually non-toxic against healthy cell linages (fibroblasts).

1-Methyl-3-(2-(sulfooxy)ethyl)-1H-imidazol-3-ium Chloride as a New and Green Ionic Liquid Catalyst for One-Pot Synthesis of Dihydropyrimidinones under Solvent-Free Condition

An efficient and simple method for the preparation of 1-methyl-3-(2-(sulfooxy)ethyl)-1H-imidazol-3-ium chloride{(MSEI)Cl}as an acidic ionic liquid is described. One-pot multicomponent condensation of 1,3-dicarbonyl compounds, urea/thiourea and aldehydes at 80∘C affords the corresponding compounds in high yields and in short reaction times by using (MSEI)Cl.

Free radical scavenging and antiproliferative properties of Biginelli adducts

A series of Biginelli adducts bearing different substituents at C-4 position were synthesized by using p-sulfonic acid calix[4]arene as a catalyst. The in vitro potential to scavenge reactive nitrogen/oxygen species (RNS and ROS) and the ability to inhibit cancer cells growth were then investigated. Four adducts were found to be potent scavengers of 2,2-diphenyl-1-picrylhydrazyl (RNS) and/or superoxide anion (ROS) radicals. The antiproliferative activity against cancer cells was disclosed for the first time for 16 monastrol analogs. The capacity of all compounds to inhibit cancer cells growth was dependent on the histological origin of cells, except for BA24, which was highly active against all cell lines. BA20 and BA33 were as potent as the reference drug doxorubicin against adriamycin-resistant ovarian and prostate cancer cells, respectively. These results highlight some monastrol analogs as lead compounds for the design of new free radical scavengers and anticancer agents.

Synthesis and biological evaluation of conformationally flexible as well as restricted dimers of monastrol and related dihydropyrimidones

A series of conformationally flexible and restricted dimers of monastrol as well as related dihydropyrimidones have been synthesized by employing one-pot Biginelli multicomponent reaction. These dimers have been evaluated for cytotoxic potency against selected human cancer cell lines and some of the compounds have exhibited more cytotoxic potency than the parent monastrol. Further, the DNA binding ability by thermal denaturation studies and antimicrobial activities of these compounds are also discussed.