Structure-activity studies of urea, carbamate, and sulfonamide derivatives of acylfulvene

Novel tetrahydronaphthalen-1-yl-phenethyl ureas: synthesis and dual antibacterial-anticancer activities

Cancer and antibiotic-resistant bacterial infections are significant global health challenges. The resistance developed in cancer treatments intensifies therapeutic difficulties. In addressing these challenges, this study synthesised a series of N,N'-dialkyl urea derivatives containing methoxy substituents on phenethylamines. Using isocyanate for the efficient synthesis yielded target products 14-18 in 73-76% returns. Subsequently, their antibacterial and anticancer potentials were assessed. Cytotoxicity tests on cancer cell lines, bacterial strains, and a healthy fibroblast line revealed promising outcomes. All derivatives demonstrated robust antibacterial activity, with MIC values ranging from 0.97 to 15.82 µM. Notably, compounds 14 and 16 were particularly effective against the HeLa cell line, while compounds 14, 15, and 17 showed significant activity against the SH-SY5Y cell line. Importantly, these compounds had reduced toxicity to healthy fibroblast cells than to cancer cells, suggesting their potential as dual-functioning agents targeting both cancer and bacterial infections.

Calcium mediated efficient synthesis of N-arylamidines from organic nitriles and amines

Amidines are a preeminent group of organic compounds having wide applications in various industries. Here, we have developed a simple one-step reaction protocol for the facile synthesis of N-arylamidines catalysed by calcium bis(hexamethyldisilazide) [Ca{N(SiMe3)2}2(THF)2]. The amidine synthesis was readily achieved from organic nitriles and amines which provided a broad substrate scope ranging from electron-withdrawing to electron-donating substitutions as well as heterocyclic substitution. The reaction was carried out in a solvent-free medium under ambient conditions. The nucleophilic addition of aromatic amines to aryl nitriles led to good to excellent yields of the corresponding amidines. The reactivity of the amidines was further examined and the respective urea derivatives were achieved in excellent yields. The plausible mechanism involves the generation of an active calcium amido pre-catalyst that helps in the activation of nitriles in the reaction course.

Hydroamination of isocyanates and isothiocyanates by alkaline earth metal initiators supported by a bulky iminopyrrolyl ligand

Synthesis of heteroleptic and homoleptic alkaline earth metal complexes supported by bulky bis-iminopyrrolyl ligands are reported. The catalytic hydroamination of isocyanates and isothiocyanates with aryl amines using calcium complex is presented.

First Synthesis for Bis-Spirothiazolidine Derivatives as a Novel Heterocyclic Framework and Their Biological Activity

BACKGROUND

Spirothiazolidines are versatile synthetic scaffold possessing wide spectrum of biological interests involving potential anticancer activity.

OBJECTIVE

To report the first synthesis of Bis Spiro-thiazolidine as a novel heterocyclic ring system.

METHODS

One-pot three-component reaction including condensation of p-phenyllene diamine; cyclohexanone and thioglycolic acid produced Spiro-thiazolidine 4, which underwent further condensation with cyclohexanone and thioglycolic acid with equimolar ratio to introduce Bis-Spiothiazolidine 5 as the first synthesis. Also, bis spiro-thiazolidine arylidene derivatives 6-13 were synthesized by the reaction of Bis-Spiothiazolidine 5 with different aromatic benzaldehydes.

RESULTS

Four compounds 13, 12, 9 and 11 have shown highly significant anticancer activity compared to Doxorubicin® (positive control) against Human liver carcinoma (HepG2) and Human Normal Retina pigmented epithelium (RPE-1) cell lines.

CONCLUSION

The novel bis-spirothiazolidine deriviatives have been synthesized for the first time and showed excellent anticancer activities compare with the corresponding spirothiazolidine derivatives.

Hydroamination of carbodiimides, isocyanates, and isothiocyanates by a bis(phosphinoselenoic amide) supported titanium(iv) complex

The hydroamination of heterocumulenes such as carbodiimides, isocyanates, and isothiocyanates by a bis(phosphinoselenoic amide) supported titanium(iv) complex as a precatalyst is reported here. The titanium(iv) complex [{Ph₂P(Se)NCH₂CH₂NPPh₂(Se)}Ti(NMe₂)₂] (1) was synthesised by the reaction of tetrakis-(dimethylamido)titanium(iv) [Ti(NMe₂)₄] with [{Ph₂P(Se)NHCH₂CH₂NHPPh₂(Se)}] in toluene at ambient temperature. Titanium complex 1 proved to be a competent pre-catalyst for the addition of an amine N-H bond to carbodiimides, isocyanates, and isothiocyanates. The reaction scope was expanded to reactions of aliphatic and aromatic amines with phenylisocyanates and phenylisothiocyanates in toluene solvents proceeding rapidly at room temperature with 5 mol% catalyst loadings to yield the corresponding urea and thio-urea derivatives up to 99%. However, ambient temperature was needed for hydroamination of 1,3-dicyclohexylcarbodiimide. The amine addition reactions with isocyanates showed first order kinetics with respect to catalyst 1 as well as substrates. The most plausible mechanism for the hydroamination reaction was established by isolating 1,1-dimethylphenyl urea as a side product.

Imidazolin-2-iminato Ligand-Supported Titanium Complexes as Catalysts for the Synthesis of Urea Derivatives

The reactions of tetrakis(dimethylamido)titanium(IV) [Ti(NMe2)4] with three different imidazolin-2-imines (Im(R)NH; R = tert-butyl (tBu), mesityl (Mes), and 2,6-diisopropylphenyl (Dipp)) afforded the corresponding titanium imidazolin-2-iminato complexes [(Im(R)N)Ti(NMe2)3] (R = tBu, 1a; R = Mes, 1b; R = Dipp, 1c). Treatment of complex 1a with two different carbodiimides [R'N═C═NR'; R' = cyclohexyl (Cy) and isopropyl (iPr)] resulted in the formation of imidazolin-2-iminato titanium mono(guanidinate) complex of the type [(Im(R)N)Ti(R'NC(NMe2)NR') (NMe2)2 (R' = iPr; R = tBu (2a), R = Dipp (2c); R' = Cy, R = tBu (3a)], as yellow solid in 94% yield. However, a similar reaction of 1b and 1c with 2 equiv of phenyl isocyanates at ambient temperature resulted in the formation of corresponding titanium bis(ureate) complexes [(Im(R)N)Ti{κ(2)-OC(NMe2)NPh}2(NMe2)] (R = Mes, 4b and R = Dipp, 4c). Three equivalents of phenyl isothiocyanate reacted with complex 1c to afford respective titanium tris(thioureate) complex [(Im(Dipp)N)Ti{κ(2)-SC(NMe2)NPh}2{κ(1)-SC(NMe2)NPh}] (6c). The molecular structures of 1a-c, 2a, 2c, 3a, 4c, and 6c were established by X-ray diffraction analyses, and, from the solid-state structures of 1a-c, 2a, 2c, 3a, 4c, and 6c, it was confirmed that the imidazolin-2-iminato titanium bond in each case is very short and possesses a multiple-bonding character. The imidazolin-2-iminato titanium complex 1c was utilized as a precatalyst for the addition of amine N-H bond to phenyl isocyanate. High yields of the corresponding urea derivatives were achieved under mild conditions. The mechanistic study of the aforementioned catalytic reaction was performed, and the active catalyst complex 7b was isolated using 2 equiv of iminopyrrole [2-(2,6-iPr2C6H3N═CH)C4H3NH] and the complex 4b. The molecular structure of 7b was thereafter established.

Efficient synthesis of 1,5-disubstituted carbohydrazones using K₂CO₃ as a carbonyl donor

A novel reaction that generates 1,5-disubstituted carbohydrazones via the carbonylation of tosylhydrazones has been developed. For the first time, the inexpensive, readily available, environmentally friendly, and nongaseous potassium carbonate is used as the carbonyl donor for the transformation. The reaction system exhibited tolerance with various functional groups and affords the desired products in good to excellent yields. This reaction is expected to be a powerful tool for the synthesis of carbohydrazone compounds.

Draft genome of Omphalotus olearius provides a predictive framework for sesquiterpenoid natural product biosynthesis in Basidiomycota

The secondary metabolome of Basidiomycota represents a largely uncharacterized source of pharmaceutically relevant natural products. Terpenoids are the primary class of bioactive compounds isolated from mushrooms. The Jack O'Lantern mushroom Omphalotus olearius was identified 50 years ago as a prolific producer of anticancer illudin sesquiterpenoids; however, to date there have been exceptionally few studies into the biosynthesis of these important compounds. Here, we report the draft genome sequence of O. olearius, which reveals a diverse network of sesquiterpene synthases and two metabolic gene clusters associated with illudin biosynthesis. Characterization of the sesquiterpene synthases enabled a comprehensive survey of all currently available Basidiomycota genomes, thereby creating a predictive resource for terpenoid natural product biosynthesis in these organisms. Our results will facilitate discovery and biosynthetic production of unique pharmaceutically relevant bioactive compounds from Basidiomycota.

Biosynthesis of terpenoid natural products in fungi

Tens of thousands of terpenoid natural products have been isolated from plants and microbial sources. Higher fungi (Ascomycota and Basidiomycota) are known to produce an array of well-known terpenoid natural products, including mycotoxins, antibiotics, antitumor compounds, and phytohormones. Except for a few well-studied fungal biosynthetic pathways, the majority of genes and biosynthetic pathways responsible for the biosynthesis of a small number of these secondary metabolites have only been discovered and characterized in the past 5-10 years. This chapter provides a comprehensive overview of the current knowledge on fungal terpenoid biosynthesis from biochemical, genetic, and genomic viewpoints. Enzymes involved in synthesizing, transferring, and cyclizing the prenyl chains that form the hydrocarbon scaffolds of fungal terpenoid natural products are systematically discussed. Genomic information and functional evidence suggest differences between the terpenome of the two major fungal phyla--the Ascomycota and Basidiomycota--which will be illustrated for each group of terpenoid natural products.

Quantification of acylfulvene- and illudin S-DNA adducts in cells with variable bioactivation capacities

Illudin S and its semisynthetic analogue acylfulvene (AF) are structurally similar but elicit different biological responses. AF is a bioreductive alkylating anticancer agent with a favorable therapeutic index, while illudin S is in general highly toxic. AF toxicity is dependent on the reductase enzyme prostaglandin reductase 1 (PTGR1) for activation to a cytotoxic reactive intermediate. While illudin S can be metabolized by PTGR1, available data suggest that its toxicity does not correspond with PTGR1 function. The goal of this study was to understand how drug cytotoxicity relates to cellular bioactivation capacity and the identity and quantity of AF- or illudin S-DNA adducts. The strategy involved identification of novel illudin S-DNA adducts and their quantitation in a newly engineered SW-480 colon cancer cell line that stably overexpresses PTGR1 (PTGR1-480). These data were compared with cytotoxicity data for both compounds in PTGR1-480 versus normal SW-480 cells, demonstrating that AF forms more DNA adducts and is more cytotoxic in cells with higher levels of PTGR1, whereas illudin S cytotoxicity and adduct formation are not influenced by PTGR1 levels. Results are discussed in the context of an overall model for how changes in relative propensities of these compounds to undergo cellular processes, such as bioactivation, contributes to DNA damage, and cytotoxicity.

Unprecedented "In Water" imidazole carbonylation: paradigm shift for preparation of urea and carbamate

The first "In Water" imidazolecarbonylation of amine is described. A one pot reaction of carbonylimidazolide in water with a nucleophile provides an efficient and general method for the preparation of urea, carbamates and thiocarbamates. Use of an anhydrous solvent and an inert atmosphere could be avoided. Product precipitate out from the reaction mixture and can be obtained in high purity by filtration, resulting in a simple and scalable method.