Synthesis and in vitro anticancer activity of pyrazolo[1,5-a]pyrimidines and pyrazolo[3,4-d][1,2,3]triazines

A novel series of pyrazolo[1,5-a]pyrimidines 14a–j and pyrazolo[1,5-a]quinazolines 18a, b were synthesized via condensation of 5-amino-1H-pyrazoles 10a, b with 3-(dimethylamino)-1-aryl-prop-2-en-1-ones 11a–e and 2-((dimethylamino)methylene)-5,5-dimethylcyclohexane-1,3-dione (15), respectively, in glacial acetic acid. Finally, treatment of 10a, b with sodium nitrite (NaNO₂) afforded pyrazolo[3,4-d]triazines 20a, b. Structures of compounds were confirmed by their spectral data. These compounds were screened for their in vitro cytotoxic activities against human cancer cell lines (HepG-2 and MCF-7) using 3-[4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. The results reveal that, the compounds 14b and 14h were the most potent in comparison with doxorubicin. The structure–activity relationship was discussed.     

Synthesis and Antimicrobial Activity of Some New 5-Arylazothiazole,Pyrazolo[1,5-a] Pyrimidine, [1,2,4]Triazolo[4,3-a]Pyrimidine,and Pyrimido[1,2-a]Benzimidazole Derivatives Containing the Thiazole Moiety

1-(2-(4,5-Dihydro-3-(4-methyl-2-phenylthiazol-5-yl)-5-phenylpyrazol-1-yl)-4-substituted thiazol-5-yl)-2-phenyldiazene were synthesized from hydrazonoyl halides and 3-(4-methyl-2-phenyl-1,3-thiazol-5-yl)-5-phenyl-4,5-dihydro-1H-pyrazole-1-carbothioamide in ethanolic triethylamine. Also, pyrazolo[5,1-a]pyrimidines, 2,3,6-trisubstituted pyridines, and pyrazolo[3,4-d]pyridazines were obtained from sodium salt of 3-hydroxy-1-(4-methyl-2-phenylthiazol-5-yl)prop-2-en-1-one and different heterocyclic amines. All structures of the newly synthesized compounds were elucidated by elemental analysis, spectral data, and alternative synthetic route whenever possible. The newly synthesized compounds were tested towards different microorganisms.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Cyanothioacetanilide Intermediates in Heterocyclic Synthesis,Part 1: Synthesis and Biological Evaluation of Some Novel Thiazole,Thiophene, Pyrazole,and Pyrazolo[1,5-a]Pyrimidine Derivatives

Some novel thiophenes (4a,b, 5, and 9a,b) were obtained from the cycloalkylation of the thiocarbamoyl group in the cyanothioacetanilide derivative (1) with α-halocarbonyl compounds. Also, the reaction of cyanothioacetanilide derivative with phenyl isothiocyanate in the presence of potassium hydroxide followed by in situ heterocyclization of the resulting adduct with α-halocarbonyl compounds furnished the corresponding thiazole (12, 14, and 15), pyrazole (19), and pyraozlo[1,5-a]pyrimidine (22, 25, and 26) derivatives. Compounds (4b, 5, 9a, 12, 13, 18, 22, 25, and 26) were tested to evaluate their antimicrobial activity.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Water-Mediated Selective Synthesis of Pyrazolo[1,5-a]quinazolin-5(4H)-ones and [1,2,4]Triazolo[1,5-a]quinazolin-5(4H)-one via Copper-Catalyzed Cascade Reactions

A convenient and sustainable synthesis of pyrazolo[1,5-a]quinazolin-5(4H)-ones and [1,2,4]triazolo[1,5-a]quinazolin-5(4H)-one through copper-catalyzed cascade reactions of 2-bromobenzoates with 1H-pyrazol-5-amines or 1H-1,2,4-triazol-5-amine under ligand-free conditions in water is presented. It is notable that aqueous medium turned out to be crucial for the chemoselective formation of the title compounds. Compared with literature protocols, this new method showed advantages such as simple and sustainable procedure, commercially available starting materials, and convenient reuse of the reaction medium together with the copper catalyst.     

Copper(I)-Catalyzed Tandem Cyclization/Condensation Reaction to Novel 4,5-Dihydropyrazolo[1,5-a]quinolines and Pyrazolo[1,5-a]indoles

A facile copper(I)-catalyzed tandem reaction for the synthesis of 4,5-dihydropyrazolo[1,5-a]quinolines and pyrazolo[1,5-a]indoles is reported here. High efficiency and good yields are displayed in this transformation under mild reaction conditions.      

Design, Synthesis, and Hypnotic Activity of Pyrazolo [1,5-a]pyrimidine Derivatives

On the basis of the Zaleplon structure, novel pyrazolo[1,5-a]pyrimidines were designed and prepared for studies on their hypnotic activity. This paper reported the synthesis of twelve new 5-methyl-7-substituted-pyrazolo[1,5-a]pyrimidine-3-carbonitrile derivatives by using simple starting materials such as propane dinitrile and triethyl orthoformate. The structures of the derived target compounds were confirmed by their IR and ^1H-NMR spectroscopic data. The preliminary pharmacological evaluations indicated that some compounds showed hypnotic activity, whilc derivative 1c was the most potent one.     

Azolo[1,5-a]pyrimidines and Their Condensed Analogs with Anticoagulant Activity

Hypercytokinemia, or cytokine storm, is one of the severe complications of viral and bacterial infections, involving the release of abnormal amounts of cytokines, resulting in a massive inflammatory response. Cytokine storm is associated with COVID-19 and sepsis high mortality rate by developing epithelial dysfunction and coagulopathy, leading to thromboembolism and multiple organ dysfunction syndrome. Anticoagulant therapy is an important tactic to prevent thrombosis in sepsis and COVID-19, but recent data show the incompatibility of modern direct oral anticoagulants and antiviral agents. It seems relevant to develop dual-action drugs with antiviral and anticoagulant properties. At the same time, it was shown that azolo[1,5-a]pyrimidines are heterocycles with a broad spectrum of antiviral activity. We have synthesized a new family of azolo[1,5-a]pyrimidines and their condensed polycyclic analogs by cyclocondensation reactions and direct CH-functionalization and studied their anticoagulant properties. Five compounds among 1,2,4-triazolo[1,5-a]pyrimidin-7-ones and 5-alkyl-1,3,4-thiadiazolo[3,2-a]purin-8-ones demonstrated higher anticoagulant activity than the reference drug, dabigatran etexilate. Antithrombin activity of most active compounds was confirmed using lipopolysaccharide (LPS)-treated blood to mimic the conditions of cytokine release syndrome. The studied compounds affected only the thrombin time value, reliably increasing it 6.5–15.2 times as compared to LPS-treated blood.     

Design,synthesis and antiproliferative activity of novel 2,7-disubstituted triazolo[1,5-a]pyrimidines

In our efforts to identify novel potent anticancer agents, we synthesized a series of 2,7-disubstituted triazolo[1,5-a]pyrimidines (6–16). Their antiproliferative activity against Bel-7402, HT-1080 and WI-38 cell lines was tested by MTT assay in vitro. Four of the compounds (9–11 and 16) displayed promising antiproliferative activity superior to gefitinib, especially compound 9. A preliminary SAR study of these derivatives was performed.     

Pyrazolo[1,5-a]pyrimidine-Dioxaborinine Hybrid Dyes: Synthesis and Substituent Effect in the Photophysical Properties

A novel family of pyrazolo[1,5-a]pyrimidine-dioxaborinine (PP-DB) hybrid dyes was synthesized by the direct construction of the dioxaborinine (DB) fragment on the pyrazolo[1,5-a]pyrimidine (PP) ring, which implies the formation of four new bonds in a one-pot manner. The dyes’ optical properties were investigated and compared with the starting pyrazolo[1,5-a]pyrimidines; a study evidencing large fluorescence quantum yields in products (φ_f up to 69 %) due to an intramolecular charge transfer (ICT) process from the PP core to a ring of DB (PP→DB) that is absent in precursors (φ_f=0.03–0.30). Time-dependent density functional theory (TD-DFT) calculations confirmed the fluorescence process involved in the novel dyes, where their ICT limits the non-radiative process due to the restricted rotation in the D−A system. The present work provides insight into how phenyl and DB ring incorporation impact the optical properties of this new group of hybrids dyes based on PP-DB.     

Synthesis and Antiproliferative Activity of Novel [1,2,4]Triazolo[1,5-a]pyrimidine-7-amine Derivatives

A series of novel N-anilino-2-substituted-5-methyl-[1,2,4]triazolo[1,5-a]pyrimidine-7-amine derivatives was prepared and evaluated for their in vitro antiproliferative activity against two cancer cell lines,Bel-7402 and HT-1080.Most of the compounds inhibited the cell proliferation at a low concentration.Seven compounds,VI5,VI7,VI10,and VI12―VI15,possessed marked antiproliferative activity superior to that of cisplatin.Of these seven initial hits,compound VI10 was the most active.     

新型吡唑并[1,5-a]嘧啶-氮芥衍生物的设计、合成及抗肿瘤活性研究

吡唑并嘧啶是一类具有广泛生物活性的杂环结构母体,同时,氮芥类药物被广泛应用于临床治疗癌症.本文基于药物设计的拼合原理,以简单易得的原料制备了取代吡唑并[1,5-a]嘧啶中间体,通过将其与苯胺氮芥组分进行拼接,合成了一系列新型吡唑并[1,5-a]嘧啶-氮芥化合物,并评估了目标化合物对五种不同肿瘤细胞(HepG2、SH-S...     

Synthesis of some novel pyrazolo[1,5-a]quinazolines and their fused derivatives

New pyrazolo[1,5-a]quinazoline-3-carbonitriles 4a,b were obtained via cyclocondensation of 5-amino-3-cyanomethyl-1H-pyrazole-4-carbonitrile (1) with enaminones of 1,3-cyclohexanedione derivatives 2a,b in refluxing glacial acetic acid. Condensation of compounds 4a,b with various aromatic aldehydes furnished the corresponding arylidene derivatives 6a–j. On the other hand, condensation of 4a,b with o-hydroxybenzaldehydes yielded the polyheterocyclic compounds 10a–h. Coupling of compounds 4a,b with aryldiazonium chlorides led to formation of 2-arylhydrazono derivatives 12a–h. Also, reaction of compounds 4a,b with phenyl isothiocyanate, followed by addition of ethyl chloroacetate and chloroacetonitrile, afforded the polyheterocyclic compounds based on pyrazolo[1,5-a]quinazoline core. The reaction of compounds 4a,b with phenyl isothiocyanate and elemental sulfur gave the thiazole-2-thione derivatives 25a,b. The reaction of enamines of compounds 4a,b with each of hydrazine hydrate and guanidine hydrochloride afforded pyrazolo[4″,3″:5′,6′]pyrido[4′,3′:3,4]pyrazolo[1,5-a]quinazolin-8-ones 30a,b and pyrimido[5″,4″:5′,6′]pyrido[4′,3′:3,4]pyrazolo[1,5-a]quinazolin-9(10H)-ones 33a,b, respectively. The structures of all the newly synthesized compounds were elucidated by elemental analyses and spectral data. The plausible mechanisms have been postulated to account for their formation.     

Recent synthetic methodologies for pyrazolo[1,5-a]pyrimidine

The development of new synthetic routes towards pyrazolo[1,5-a]pyrimidines for their biological and medicinal exploration is an attractive area for researchers. This review focuses on various synthetic routes developed in the last decade for the synthesis of differently substituted pyrazolo[1,5-a]pyrimidines by a broad range of organic reactions by means of 5-aminopyrazole as a precursor.     

Functional Pyrazolo[1,5-a]pyrimidines: Current Approaches in Synthetic Transformations and Uses As an Antitumor Scaffold

Pyrazolo[1,5-a]pyrimidine (PP) derivatives are an enormous family of N-heterocyclic compounds that possess a high impact in medicinal chemistry and have attracted a great deal of attention in material science recently due to their significant photophysical properties. Consequently, various researchers have developed different synthesis pathways for the preparation and post-functionalization of this functional scaffold. These transformations improve the structural diversity and allow a synergic effect between new synthetic routes and the possible applications of these compounds. This contribution focuses on an overview of the current advances (2015–2021) in the synthesis and functionalization of diverse pyrazolo[1,5-a]pyrimidines. Moreover, the discussion highlights their anticancer potential and enzymatic inhibitory activity, which hopefully could lead to new rational and efficient designs of drugs bearing the pyrazolo[1,5-a]pyrimidine core.     

Synthesis of Novel Disubstituted Pyrazolo[1,5‐a]pyrimidines,Imidazo[1,2‐a]pyrimidines,and Pyrimido[1,2‐a]benzimidazoles Containing Thioether and Aryl Moieties

A series of novel 6‐[(1,3,4‐thiadiazol‐2‐yl)sulfanyl]‐7‐phenylpyrazolo[1,5‐a]pyrimidines, 5‐phenyl‐6‐[(1,3,4‐thiadiazol‐2‐yl)sulfanyl]imidazo[1,2‐a]pyrimidines, and 2‐phenyl‐3‐[(1,3,4‐thiadiazol‐2‐yl)sulfanyl]pyrimido[1,2‐a]benzimidazoles have been synthesized in four steps starting with 2‐hydroxyacetophenone. The intermediate 3‐[(1,3,4‐thiadiazol‐2‐yl)sulfanyl]‐4H‐1‐benzopyran‐4‐ones reacted with pyrazol‐3‐amines, 5‐methylpyrazol‐3‐amine, and 1H‐imidazol‐2‐amine, 1H‐benzimidazol‐2‐amine via a cyclocondensation to give the title compounds in the presence of MeONa as base, respectively. The approach affords the target compounds in acceptable‐to‐good yields. The new compounds were characterized by their IR, NMR, and HR mass spectra.     

吡唑[1,5-a]并吡啶-3-羧酸衍生物合成方法的改进

以取代吡啶为原料,在羟胺-O-磺酸的作用下,得到取代的N-氨基吡啶的硫酸盐,再通过1,3-偶极环加成反应,与丙炔酸乙酯生成吡唑[1,5-a]并吡啶-3-羧酸乙酯衍生物,然后在质量分数30%的NaOH水溶液作用下水解成酸。 该方法将取代的N-氨基吡啶的硫酸盐直接投入到下步反应,省去传统方法中将硫酸盐转化为碘盐的步骤,解决了碘盐不易析出的问题,并将取代的N-氨基吡啶硫酸盐和丙炔酸乙酯分别用水和二甲基甲酰胺溶解后再混合,增加了原料和K₂CO₃在体系中的溶解性,提高了产率。 本文成功合成了6种化合物(4a~4f),产率为88%~93%,该方法条件温和,后处理简单,成本低,是适合大规模生产的新工艺。     

Synthesis of novel isoxazolyl bis-thiazolo[3,2-a]pyrimidines

A new synthetic strategy for the synthesis of novel 3-(3-(3-methyl-4-nitroisoxazol-5-yl)-2-phenyl-1-(5,7-diaryl-7H-thiazolo[3,2-a]pyrimidin-3-yl)propyl)-5,7-diaryl-7H-thiazolo[3,2-a] pyrimidines(7a-i) analogues is described.Reaction of 3-(2(3-methyl-4-nitroisoxazole-5-yl)-1-phenylethyl)pentane-2,4-dione(3) with two moles of thiourea in presence of iodine and CuO afforded 4-(1-(2-aminothiazol-4-yl)-3-(3-methyl-4-nitroisoxazol-5-yl)-2-aryl propyl-thiazol-2-amine(5).Compound 5 on reaction with two moles of chalcone(6) furnished novel 3-(3-(3-methyl-4-nitroisoxazol-5-yl)-2-phenyl-1-(5,7-diaryl-7H-thiazolo[3,2a]pyrimidin-3-yl)propyl)-5,7-diaryl-7H-thiazolo[3,2-a] pyrimidines(7a-i).     

Synthesis of Some New 6,8‐Disubstituted 7,8‐Dihydropyrimido[2,3:4,3]pyrazolo[1,5‐a]pyrimidines and 6,7,8‐Trisubstituted Pyrimido[2,3:4,3]Pyrazolo[1,5‐a]Pyrimidine Derivatives

Cyclization of 5‐cyano‐1,6‐dihydro‐4‐methyl‐2‐phenyl‐6‐thioxopyrimidine 4 with excess of 85% hydrazine hydrate afforded the 3‐amino‐4‐methyl‐6‐phenylpyrazolo[3,4‐d]pyrimidine 5 , which can react with appropriate Mannich base derivatives 13a‐c and chalcones 27a,b to yield the corresponding 6,8‐disubstituted 7,8‐dihydropyrimido[2,3:4,3]pyrazolo[1,5‐a]pyrimidines 15a‐c and 30a,b , respectively. On the other hand, the 6,7,8‐trisubstituted pyrimido[2,3:4,3]pyrazolo[1,5‐a]pyrimidine derivatives 8a‐g, 20a‐e, 36 and 38 were obtained by treatment of compound 5 with appropriate 1,3‐diketones 6a‐g , 3‐dimethylamino‐1‐(substituted)prop‐2‐enones 18a‐e , 3‐aminocrotononitrile 3 , and ethoxymethylenemalononitrile 37 under acidic condition, respectively.     

微波辐射下合成2-甲硫基-3-氰基-7-取代苯基吡唑并[1,5-a]嘧啶及生物活性的研究

利用取代烯胺酮1与3-甲硫基-4-氰基-5-氨基-1H-吡唑(2)反应,用传统和微波2种方法合成了6种化合物2-甲硫基-3-氰基-7-取代苯基吡唑并[1,5-a]嘧啶(3a～3f),化合物的结构均经元素分析,IR,1H NMR所证实.对比两种方法,微波辐射具有用时少、环境友好、易纯化和产率高的特点,同时,探讨了反应可能的机理,并对所有化合物的杀菌和除草活性进行了测试.