Design, synthesis, and biological evaluation of 4‐aminopyrimidine or 4,6‐diaminopyrimidine derivatives as beta amyloid cleaving enzyme‐1 inhibitors

Microwave-Assisted One-Pot Telescoped Synthesis of 2-Amino-1,3-thiazoles, Selenazoles, Imidazo[1,2-a]pyridines, and Other Heterocycles from Alcohols

Primary and secondary alcohols have been converted into 2-amino-1,3-thiazoles under microwave irradiation, employing trichloroisocyanuric acid (TCCA) as a dual oxidant and chlorine source, TEMPO as a co-oxidant, and thiourea. Secondary alcohols underwent a single-stage, one-pot conversion process, while primary alcohols required a two-stage, one-pot procedure. Both transformations were completed within minutes (25-45 min). The versatility of this protocol extends to the synthesis of other heterocycles, including 1,3-selenazoles, 2-aminoimidazoles, imidazo[1,2-a]pyridines, quinoxalines, and hydrazino thiazoles by replacing thiourea with the appropriate surrogates.

NH4I-promoted electrosynthesis of 2-aminothiazole derivatives from ketone compounds and NH4SCN

A novel and efficient electrochemical synthesis of 2-aminothiazole derivatives from ketones and NH4SCN is described. Under the co-action of NH3 and iodine free radicals or iodine (I2) electrochemically generated in situ, the target product 2-aminothiazole derivatives could be successfully obtained in good to excellent yields.

Design, synthesis and antiproliferative activity of novel 2,4-diamino-5-methyleneaminopyrimidine derivatives as potential anticancer agents

In order to discover new anticancer agents, 25 novel 2,4-diamino-5-methyleneaminopyrimidine derivatives were designed and synthesized based on our previous work via a ring-opening strategy. Among them, compared with 5-FU, compound 7i exhibited 4.9-, 2.9-, 2.1-, and 3.0-fold improvement in inhibiting HCT116, HT-29, MCF-7, and HeLa cells proliferation with IC₅₀ values of 4.93, 5.57, 8.84, and 14.16 μM, respectively. Moreover, further mechanistic studies indicated that compound 7i could concentration-dependently induce cell cycle arrest and apoptosis in HCT116 cells. These findings revealed that 2,4-diamino-5-methyleneaminopyrimidine scaffold has potential for further investigation to explore novel anticancer agents.

Synthesis, antioxidant and antimicrobial properties of novel pyridyl-carbonyl thiazoles as dendrodoine analogs

Marine compound dendrodoine was first obtained from tunicate species ( Dendrodo grossularia ). It has a five-membered ring, namely, it is a heterocycle thiadiazole, which is found rarely in natural sources . Following its biological activities, novel analogs have been investigated recently. Synthesis of the analogs for this study is realized with uncommon thiazole closure, including methylene-carbonyl condensation. Structures are elucidated by NMR ( ¹ , ¹³ C) and HRMS spectrums. As an alkaloid derivative, antioxidant properties were evaluated with DPPH and FRAP assays and antimicrobial effect with microdilution method. Among the series, 3bc-3cf showed higher antioxidant activity than those having 3 or 4-pyridyl substituents. There is lesser activity for 2-pyridyl activity for 2-pyridyl containing group, which may be a result of intramolecular interactions. No activity was observed against gram-negative bacteria at 250 μg/mL. 3ae and 3ce showed activity at 64 μg/mL against S. aureus and 3ae showed activity at 16 μg/mL against S. epidermidis gram-positive bacteria. Chloramphenicol showed activity against all microorganisms at 8–16 μg/mL. Sixteen original dendrodoine analogs have been defined by close/higher activity compared to dendrodoine analogs and Trolox.

Synthesis, molecular docking studies, and biological evaluation of novel alkyl bis(4-amino-5-cyanopyrimidine) derivatives

A series of bis(4-amino-5-cyano-pyrimidines) was synthesized and evaluated as dual inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). To further explore the multifunctional properties of the new derivatives, their antioxidant and antibacterial activities were also tested. The results showed that most of these compounds could effectively inhibit AChE and BChE. Particularly, compound 7c exhibited the best AChE inhibitory activity (IC₅₀  = 5.72 ± 1.53 μM), whereas compound 7h was identified as the most potent BChE inhibitor (IC₅₀  = 12.19 ± 0.57 μM). Molecular modeling study revealed that compounds 7c, 7f, and 7b showed a higher inhibitory activity than that of galantamine against both AChE and BChE. Anticholinesterase activity of compounds 7h, 7b, and 7c was significant in vitro and in silico for both enzymes, since these compounds have hydrophobic rings (Br-phenyl, dimethyl, and methoxyphenyl), which bind very well in both sites. In addition to cholinesterase inhibitory activities, these compounds showed different levels of antioxidant activities. Indeed, in the superoxide-dimethyl sulfoxide alkaline assay, compound 7j showed very high inhibition (IC₅₀  = 0.37 ± 0.28 μM). Also, compound 7l exhibited strong and good antibacterial activity against Staphylococcus epidermidis and Staphylococcus aureus, respectively. Taking into account the results of biological evaluation, further modifications will be designed to increase potency on different targets. In this study, the obtained results can be a new starting point for further development of multifunctional agents for the treatment of Alzheimer's disease.