Versatility of the Biginelli reaction: Synthesis of new biphenyl dihydropyrimidin-2-thiones using different ketones as building blocks

Revisiting Biginelli-like reactions: solvent effects, mechanisms, biological applications and correction of several literature reports

This study critically reevaluates reported Biginelli-like reactions using a Kamlet-Abboud-Taft-based solvent effect model. Surprisingly, structural misassignments were discovered in certain multicomponent reactions, leading to the identification of pseudo three-component derivatives instead of the expected MCR adducts. Attempts to replicate literature conditions failed, prompting reconsideration of the described MCRs and proposed mechanisms. Electrospray ionization (tandem) mass spectrometry, NMR, melting points, elemental analyses and single-crystal X-ray analysis exposed inaccuracies in reported MCRs and allowed for the proposition of a complete catalytic cycle. Biological investigations using both pure and "contaminated" derivatives revealed distinctive features in assessed bioassays. A new cellular action mechanism was unveiled for a one obtained pseudo three-component adduct, suggesting similarity with the known dihydropyrimidinone Monastrol as Eg5 inhibitors, disrupting mitosis by forming monoastral mitotic spindles. Docking studies and RMSD analyses supported this hypothesis. The findings described herein underscore the necessity for a critical reexamination and potential corrections of structural assignments in several reports. This work emphasizes the significance of rigorous characterization and critical evaluation in synthetic chemistry, urging a careful reassessment of reported synthesis and biological activities associated with these compounds.

LaSOM 335, active against bladder cancer cells, interferes with Let-60 (hRas) and reduces CD73 expression/activity

Bladder cancer is the fourth most common malignancy in men. It can present along the entire continuum of severity, from mild to well-differentiated disease to extremely malignant tumors with low survival rates. Human RAS genes are the most frequently mutated oncogenes in human cancers, and the critical role of aberrant Ras protein function in carcinogenesis is well established. Therefore, considerable efforts have been devoted to the development of anti-Ras inhibitors for cancer treatment. This study presents the biphenyl dihydropyrimidinone LaSOM 335 with high activity against T24 bladder cancer cells (IC50  = 10.73 ± 0.53 μM) and selectivity of cytotoxicity for this cancer cell line compared to two non-cancer cell lines investigated. Furthermore, we also show that this compound reduced vulvar development in the mutant let-60 gene of Caenorhabditis elegans. Let-60 is a homolog of the mammalian Ras gene. In addition, we observed that LaSOM 335 inhibits the enzymatic activity of CD73 and decreases CD73 expression. Possibly, this expression decrease is due to downstream EGFR signaling via the Ras-Raf-ERK pathway, that directly regulates CD73 expression via ERK1/2. Evidence suggests that non-immunomodulating functions of CD73 play an equally important role for cancer cell survival, progression, and migration. Regarding we also notice that LaSOM 335 was safe in the in vivo model of C. elegans. The set of these findings makes this biphenyl dihydropyrimidinone a promising candidate for further investigations in the bladder cancer field.

A facile hydrothermal synthesis of high-efficient NiO nanocatalyst for preparation of 3,4-dihydropyrimidin-2(1H)-ones

The present work introduces a one-step and facile hydrothermal procedure as a green process for the first time to synthesize nickel(II) oxide (NiO) nanoparticles. The as-prepared nanomaterials were used as high efficient, low toxic and cost catalyst for the synthesis of some organic compounds. Ni(NO₃)₂ and some natural extract were used as a surfactant for the first time to synthesis NiO nanomaterials. A high synthesis yield (91%) was obtained for S₂. Rietveld analysis affirmed the cubic crystal system of the obtained NiO nanocatalyst. The morphology studies were carried out with the FESEM method and the images revealed a change from non-homogenous to homogenous spherical particles when the Barberryas was used instead of orange blossom surfactant. Besides, the images revealed that the particle size distribution was in the range of 20 to 60 nm. The synthesized catalysts were used for the first time in Biginelli multicomponent reactions (MCRs) for the preparation of 3,4-dihydropyrimidin-2(1H)-ones (DHPMs) under the present facile reaction conditions. High yield (97%) of the final product was achieved at the optimum condensation reaction conditions (Catalyst: 60 mg; temperature: 90 °C and time: 90 min) when ethyl acetoacetate/methyl acetoacetate (1 mmol), benzaldehyde (1 mmol) and urea (1.2 mmol) were used. A kinetic study affirmed pseudo-first-order model for Biginelli reactions followed the pseudo-first-order model.

The use of isoxazoline and isoxazole scaffolding in the design of novel thiourea and amide liquid-crystalline compounds

A series of novel thiourea and amide liquid crystals containing 5-membered isoxazoline and isoxazole rings were synthetized and the liquid crystal properties studied. Thioureas were obtained using a condensation reaction of benzoyl chlorides, arylamines and ammonium thiocyanate. The amides, on the other hand, were the byproduct of a quantitative reaction which used potassium cyanate as the starting material. Thiourea and amide derivatives were predominantly SmA mesophase inductors. A nematic mesophase was observed only for thioureas and amides containing an isoxazole ring. Additionaly, the liquid crystal behavior was also dependent on the relative position of nitrogen and oxygen atoms on the 5-membered heterocycle.

An efficient synthesis of 4,5-diaryl-3,4-dihydropyrimidin-2(1H)-one via a cesium carbonate-promoted direct condensation of 1-aryl-2-propanone with 1,1′-(arylmethylene)diurea

An efficient method for the synthesis of 4,5-diaryl-3,4-dihydropyrimidin-2(1H)-one by using 1,1′-(arylmethylene)diurea and 1-aryl-2-propanone as substrates was developed. The reactions proceeded efficiently in the presence of Cs₂CO₃ to give the desired products in moderate to good yields with wide substrate scope and good functional group tolerance, serving as an attractive alternative or complement to the previously reported methods for the facile assembly of biologically and pharmaceutically active 3,4-dihydropyrimidin-2(1H)-ones.

A Cs₂CO₃-promoted efficient method for the synthesis of 4,5-diaryl-3,4-dihydropyrimidin-2(1H)-one by using 1,1′-(arylmethylene)diurea and 1-aryl-2-propanone as substrates was developed.

Ethyl 6-Methyl-2-oxo-4-{4-[(1-phenyl-1H-1,2,3-triazol-4-yl)methoxy]phenyl}-1,2,3,4-tetrahydropyrimidine-5-carboxylate

The Biginelli reaction is an acid-catalyzed, three-component reaction between an aldehyde, a hydrogen methylene active compound, and urea (or its analogue) and constitutes a rapid and easy synthesis of highly functionalized heterocycles. Synthesis of ethyl 6-methyl-2-oxo-4-{4-[(1-phenyl-1H-1,2,3-triazol-4-yl)methoxy]phenyl}-1,2,3,4-tetrahydropyrimidine-5-carboxylate, identified by our laboratory code LaSOM® 293, was achieved using the Biginelli reaction as the key step, followed by the Huisgen 1,3-dipolar cycloaddition in a convergent four-step route. The product LaSOM® 293 was obtained with a yield of 84%.

Ethyl 4-(2-fluorophenyl)-6-methyl-2-thioxo-1-(p-tolyl)-1,2,3,4-tetrahydropyrimidine-5-carboxylate

The Biginelli reaction is a highly versatile reaction that leads to dihydropyrimidinones/thiones. This scaffold is reported as being a privileged structure due to its ability to interact with biological targets. Synthesis of ethyl 4-(2-fluorophenyl)-6-methyl-2-thioxo-1-(p-tolyl)-1,2,3,4-tetrahydropyrimidine-5-carboxylate was achieved through the Biginelli reaction using a functionalized thiourea. In silico studies demonstrated that the compound title showed good potential for interacting with ecto-5’-nucleotidase, which has been considered as a target in designs for anti-cancer drugs.