Efficient Synthesis of (1,2,3-Triazol-1-yl)methylpyrimidines from 5-Bromo-1,1,1-trifluoro-4-methoxypent-3-en-2-one

Chemoselective O-Alkylation of 4-(Trifluoromethyl)pyrimidin-2(1H)-ones Using 4-(Iodomethyl)pyrimidines

This study reports two strategies for preparing O-alkyl derivatives of 6-substituted-4-(trifluoromethyl)pyrimidin-(1H)-ones: a linear protocol of alkylation, using a CCC-building block followed by [3 + 3]-type cyclocondensation with 2-methylisothiourea sulfate and a convergent protocol based on direct alkylation, using 4-(iodomethyl)-2-(methylthio)-6-(trihalomethyl)pyrimidines. It was found that the cyclocondensation strategy is not feasible; thus, the direct chemoselective O-alkylation was performed, and 18 derivatives of the targeted pyrimidines were obtained in 70-98% yields. The structure of the products was unambiguously determined via single crystal X-ray analyses and two-dimensional nuclear magnetic resonance experiments.

Synthesis of Methylene-Bridged Trifluoromethyl Azoles Using 5-(1,2,3-Triazol-1-yl)enones

A protocol for synthesizing triazole-containing pyrazolines and pyrazoles selectively using trifluoromethylated 5-(1,2,3-triazol-1-yl)enones as starting materials, is reported. The selectivity of the reaction was controlled by the nature of the hydrazine or derivative used: free hydrazines furnished the 1,5-regiosiomer exclusively in yields up to 98%, whereas protected hydrazines provided the 1,3-regioisomer in yields up to 77%. To demonstrate the synthetic versatility of the triazole-based enone, reactions with other unsymmetrical dinucleophiles (hydroxylamine hydrochloride and S-methyl isothiourea sulfates) allowed the selective preparation of triazole-containing isoxazoline and pyrimidine rings.

Ultrasound-assisted synthesis of pyrimidines and their fused derivatives: A review

The pyrimidine scaffold is present in many bioactive drugs; therefore, efficient synthetic routes that provide shorter reaction times, higher yields, and site-selective reactions are constantly being sought. Ultrasound (US) irradiation has emerged as an alternative energy source in the synthesis of these heterocyclic scaffolds, and over the last ten years there has been a significant increase in the number of publications mentioning US in either the construction or derivatization of the pyrimidine core. This review presents a detailed summary (with 140 references) of the effects of US (synergic or not) on the construction and derivatization of the pyrimidine core through classical reactions (e.g., multicomponent, cyclocondensation, cycloaddition, and alkylation reactions). The main points that were taken into consideration are as follows: chemo- and regioselectivity issues, and the results of conventional heating methods compared to US and mechanistic insights that are also presented and discussed for key reactions.

Antiparasitic activities of novel pyrimidine N-acylhydrazone hybrids

In this article, a series of 29 new pyrimidine N-acylhydrazone hybrids were synthesized and evaluated in vitro against Leishmania amazonensis and Trypanosoma cruzi protozoa that cause the neglected diseases cutaneous leishmaniasis and Chagas disease, respectively. Eight of the target compounds showed significant antiprotozoal activities with IC₅₀ values in 4.3-33.6 μM range. The more active compound 4f exhibited selectivity index greater than 15 and drug-like properties based on Lipinski's rule.

Cesium carbonate-promoted synthesis of aryl methyl sulfides using S-methylisothiourea sulfate under transition-metal-free conditions

In the presence of cesium carbonate, an efficient synthesis of aryl methyl sulfides by the reactions of aryl halides with commercially available S-methylisothiourea sulfate is developed. This odourless and highly crystalline solid can be used as the substitute for malodorous methanethiol. The gram-scale reaction also proceeds smoothly without the use of column chromatography separation. Similarly, 2-(dimethylamino)ethylthio and cyclopropylmethylthio groups can be easily introduced into the aromatic rings from the corresponding S-[2-(dimethylamino)ethyl]isothiourea dihydrochloride and S-cyclopropylmethylisothiourea hydrobromide. The possible reaction mechanism is proposed. It is believed that this route to aryl alkyl sulfides is well competitive with currently known methods due to its wide substrate scope, excellent yields, easy operation and transition-metal-free conditions.