Anticancer evaluations of iodoquinazoline substituted with allyl and/or benzyl as dual inhibitors of EGFRWT and EGFRT790M: design, synthesis, ADMET and molecular docking.

Fifteen new iodoquinazoline derivatives, 5a,b to 18, are reported in this study and their anticancer evaluation as dual inhibitors of EGFRWT and EGFRT790M. The new derivatives were designed according to the target of structural requirements of receptors. Cytotoxicity of our compounds was evaluated against MCF-7, A549, HCT116 and HepG2 cell lines using MTT assay. Compounds 18, 17 and 14b showed the highest anticancer effects with IC50 = 5.25, 6.46, 5.68 and 5.24 µM, 5.55, 6.85, 5.40 and 5.11 µM and 5.86, 7.03, 6.15 and 5.77 µM against HepG2, MCF-7, HCT116 and A549 cell lines, respectively. The eight highly effective compounds 10, 13, 14a, 14b, 15, 16, 17 and 18 were inspected against VERO normal cell lines to evaluate their cytotoxicity. Our conclusion was that compounds 10, 13, 14a, 14b, 15, 16, 17 and 18 possessed low toxicity against VERO normal cells with IC50 increasing from 43.44 to 52.11 µM. All compounds were additionally assessed for their EGFRWT and EGFRT790M inhibitory activities. Additionally, their ability to bind with EGFRWT and EGFR receptors was confirmed by molecular docking. Compound 17 exhibited the same inhibitory activity as erlotinib. Compounds 10, 13, 14b, 16 and 18 excellently inhibited VEGFR-2 activity with IC50 ranging from 0.17 to 0.50 µM. Moreover, compounds 18, 17, 14b and 16 remarkably inhibited EGFRT790M activity with IC50 = 0.25, 0.30, 0.36 and 0.40 µM respectively. As planned, compounds 18, 17 and 14b showed excellent dual EGFRWT/EGFRT790M inhibitory activities. Finally, our compounds 18, 17 and 14b displayed good in silico ADMET calculated profiles.

2-Thioxo-3,4-dihydropyrimidine and thiourea endowed with sulfonamide moieties as dual EGFRT790M and VEGFR-2 inhibitors: Design, synthesis, docking, and anticancer evaluations.

The effectiveness of a new series of thiopyrimidine and thiourea containing sulfonamides moieties was tested on HCT-116, MCF-7, HepG2, and A549. HepG2 cell line was the one that all the new derivatives affected the most. The greatest potent compounds against the four HepG2, HCT116, MCF-7, and A549 cell lines were 8f and 8g with IC50 = 4.13, 6.64, 5.74, 6.85 µM and 4.09, 4.36, 4.22, 7.25 µM correspondingly. Compound 8g exhibited higher activity than sorafenib against HCT116 and MCF-7 but exhibited lower activity against HepG2 and A549. Moreover, compounds 8f and 8g exhibited higher activities than erlotinib on HepG2, HCT116, and MCF-7 but demonstrated lower activity on A549. The most potent cytotoxic derivatives 6f, 6g, 8c, 8d, 8e, 8f, and 8g were examined on normal VERO cell lines. Our derivatives have low toxicity on VERO cells with IC50 values ranging from 32.05 to 53.15 µM. Additionally, all compounds were assessed for dual VEGFR-2 and EGFRT790M inhibition effects. Compounds 8f and 8g were the most potent derivatives inhibited VEGFR-2 at IC50 value of 0.88 and 0.90 µM, correspondingly. As well, derivatives 8f and 8g could inhibit EGFRT790M demonstrating strongest effects with IC50 = 0.32 and 0.33 µM sequentially. Additionally, the greatest active derivatives ADMET profile was evaluated in relationship with sorafenib and erlotinib as reference agents. The data attained from docking were greatly related to that achieved from the biological testing.

Tailored horseshoe-shaped nicotinonitrile scaffold as dual promising c-Met and Pim-1 inhibitors: Design, synthesis, SAR and in silico study.

For the horseshoe tactic to succeed in inhibiting c-Met and Pim-1, the nicotinonitrile derivatives (2a-n) were produced in high quantities by coupling acetyl phenylpyrazole (1) with the proper aldehydes and ethyl cyanoacetate under basic conditions. Consistent basic and spectroscopic data (NMR, IR, Mass, and HPLC) supported the new products' structural findings. With IC50 potency in nanomolar ranges, these compounds had effectively repressed them, particularly compounds 2d and 2 h, with IC50 values below 200 nM. The most potent compounds (2d and 2 h) were tested for their antitumor effects against prostate (PC-3), colon (HCT-116), and breast (MDA-MB-231) and were evaluated in comparison to the anticancer drug tivantinib using the MTT assay. Similar to tivantinib, these compounds showed good antiproliferative properties against the HCT-116 tumor cells while having low cytotoxicity towards healthy fetal colon (FHC) cells. In the HCT-116 cell line, their ability to trigger the apoptotic cascade was also investigated by looking at the level of Bax and Bcl-2 as well as the activation of the proteolytic caspase cascade. When HCT-116 cells were exposed to compounds 2d and 2 h in comparison to the control, active caspase-3 levels increased. The HCT-116 cell line also upregulated Bcl-2 protein levels and downregulated Bax levels. Additionally, when treated with compound 2d, the HCT-116 cell cycle was primarily stopped at the S phase. Compared to the control, compound 2d treatment significantly inhibited the protein expression levels of c-Met and Pim-1 kinases in the treated HCT-116 cells. Thorough molecular modeling analyses, such as molecular docking and dynamic simulation, were performed to ascertain the binding mechanism and stability of the target compounds.

Five and six membered heterocyclic rings endowed with azobenzene as dual EGFRT790M and VEGFR-2 inhibitors: design, synthesis, in silico ADMET profile, molecular docking, dynamic simulation and anticancer evaluations.

Novel azobenzene scaffold-joined heterocyclic isoxazole, pyrazole, triazole, and/or triazine moieties have been developed and synthesized utilizing microwave and traditional methods. Our compounds were tested for growth inhibition of A549, MCF-7, HCT-116, and HepG2 tumors by dual targeting the VEGFR-2 and EGFRT790M enzymes. The suggested compound's manner of binding with EGFRT790M and VEGFR-2 active sites was explored through molecular design and MD modeling. The information from the results of the biological screening and the docking studies was highly correlated. The A549 cell line was the one that responded to the novel compound's effects most effectively. Having IC50 values of 5.15, 6.37, 8.44 and 6.23 µM, respectively, 14 was the most effective derivative on the four A549, MCF-7, HCT116 and HepG2 cancer cells. It had greater activity than erlotinib and slightly inferior activities on the tested cell lines than sorafenib, respectively. The cytotoxicity of the most effective derivatives, 5, 6, 10 and 14, was evaluated against typical VERO cell lines. Having IC50 values ranging from 42.32 to 55.20 µM, the results showed that the investigated drugs have modest toxicity against VERO normal cells. Additionally all derivatives were assessed for their dual VEGFR-2 and EGFRT790M inhibitory effects. Among them, derivatives 14, 5 and 10 were established as the greatest inhibitors of VEGFR-2 at IC50 values of 0.95, 1.25 and 1.50 µM correspondingly. As well, derivatives 14, 6, 5 and 10 could inhibit EGFRT790M activity demonstrating strongest effects with IC50 = 0.25, 0.35, 0.40 and 0.50 µM respectively. Furthermore, the ADMET profile was evaluated for compounds 5, 6, 10 and 14 in contrast to reference drugs sorafenib and erlotinib.

Design, synthesis, and docking of novel thiazolidine-2,4-dione multitarget scaffold as new approach for cancer treatment.

Novel thiazolidine-2,4-diones have been developed and estimated as conjoint inhibitors of EGFRT790M and VEGFR-2 against HCT-116, MCF-7, A549, and HepG2 cells. Compounds 6a, 6b, and 6c were known to be the dominant advantageous congeners against HCT116 (IC50 = 15.22, 8.65, and 8.80 µM), A549 (IC50 = 7.10, 6.55, and 8.11 µM), MCF-7 (IC50 = 14.56, 6.65, and 7.09 µM) and HepG2 (IC50 = 11.90, 5.35, and 5.60 µM) mass cell lines, correspondingly. Although compounds 6a, 6b, and 6c disclosed poorer effects than sorafenib (IC50 = 4.00, 4.04, 5.58, and 5.05 µM) against the tested cell sets, congeners 6b and 6c demonstrated higher actions than erlotinib (IC50 = 7.73, 5.49, 8.20, and 13.91 µM) against HCT116, MCF-7 and HepG2 cells, yet lesser performance on A549 cells. The hugely effective derivatives 4e-i and 6a-c were inspected versus VERO normal cell strains. Compounds 6b, 6c, 6a, and 4i were found to be the most effective derivatives, which suppressed VEGFR-2 by IC50 = 0.85, 0.90, 1.50, and 1.80 µM, respectively. Moreover, compounds 6b, 6a, 6c, and 6i could interfere with the EGFRT790M performing strongest effects with IC50 = 0.30, 0.35, 0.50, and 1.00 µM, respectively. What is more, 6a, 6b, and 6c represented satisfactory in silico computed ADMET profile.

Isatin-pyrimidine hybrid derivatives as enoyl acyl carrier protein reductase (InhA) inhibitors against Mycobacterium tuberculosis.

Tuberculosis is a worldwide problem that impose a burden on the economy due to continuous development of resistant strains. The development of new antitubercular drugs is a need and can be achieved through inhibition of druggable targets. Mycobacterium tuberculosis enoyl acyl carrier protein (ACP) reductase (InhA) is an important enzyme for Mycobacterium tuberculosis survival. In this study, we report the synthesis of isatin derivatives that could treat TB through inhibition of this enzyme. Compound 4l showed IC50 value (0.6 ± 0.94 µM) similar to isoniazid but is also effective against MDR and XDR Mycobacterium tuberculosis strains (MIC of 0.48 and 3.9 µg/mL, respectively). Molecular docking studies suggest that this compound binds through the use of relatively unexplored hydrophobic pocket in the active site. Molecular dynamics was used to investigate and support the stability of 4l complex with the target enzyme. This study paves the way for the design and synthesis of novel antitubercular drugs.

Effect of hydrophobic extension of aryl enaminones and pyrazole-linked compounds combined with sulphonamide, sulfaguanidine, or carboxylic acid functionalities on carbonic anhydrase inhibitory potency and selectivity.

Design and synthesis of three novel series of aryl enaminones (3a-f and 5a-c) and pyrazole (4a-c) linked compounds with sulphonamides, sulfaguanidine, or carboxylic acid functionalities were reported as carbonic anhydrase inhibitors (CAIs) using the "tail approach" strategy in their design to achieve the most variable amino acids in the middle/outer rims of the hCAs active site. The synthesised compounds were assessed in vitro for their inhibitory activity against the following human (h) isoforms, hCA I, II, IX, and XII using stopped-flow CO2 hydrase assay. Enaminone sulphonamide derivatives (3a-c) potently inhibited the target tumour-associated isoforms hCA IX and hCA XII (KIs 26.2-63.7 nM) and hence compounds 3a and 3c were further screened for their in vitro cytotoxic activity against MCF-7 and MDA-MB-231 cancer cell lines under normoxic and hypoxic conditions. Derivative 3c showed comparable potency against both MCF-7 and MDA-MB-231 cancer cell lines under both normoxic ((IC50 = 4.918 and 12.27 µM, respectively) and hypoxic (IC50 = 1.689 and 5.898 µM, respectively) conditions compared to the reference drug doxorubicin under normoxic (IC50 = 3.386 and 4.269 µM, respectively) and hypoxic conditions (IC50 = 1.368 and 2.62 µM, respectively). Cell cycle analysis and Annexin V-FITC and propidium iodide double staining methods were performed to reinforce the assumption that 3c may act as a cytotoxic agent through the induction of apoptosis in MCF-7 cancer cells.

Dual Targeting of VEGFR2 and C-Met Kinases via the Design and Synthesis of Substituted 3-(Triazolo-thiadiazin-3-yl)indolin-2-one Derivatives as Angiogenesis Inhibitors.

The vascular endothelial growth factor receptor 2 (VEGFR2) and c-mesenchymal epithelial transition factor (c-Met) are members of receptor tyrosine kinases which have a crucial role in the process of angiogenesis. Isatin moiety is a versatile group that is shared in many compounds targeting both c-Met and VEGFR2 kinases. In this study, we designed and synthesized different derivatives of substituted 3-(triazolo-thiadiazin-3-yl)indolin-2-one derivatives (6a-y) as dual inhibitors for c-Met and VEGFR2 enzymes. Eight compounds 6a, 6b, 6e, 6l, 6n, 6r, 6v, and 6y were assessed for their anticancer activities against a panel of 58 cancer cell lines according to the US-NCI protocol. Compound 6b revealed the most effective antiproliferative potency (GI %), with broad-spectrum activity against different subpanels of the most NCI 58 tumor cell lines. An in vivo hen's egg-chorioallantoic membrane (HET-CAM) angiogenic study was carried out for 21 compounds 6a, b, d, f, h, i, k-o, t, and 6x to check their mortality and toxicity. At 100 µM concentration, all compounds produced 100% mortality of the chick embryos. At 40 µM concentration, 13 compounds did not exhibit any detectable mortality (nontoxic) and revealed a potent antiangiogenic effect. Seven compounds 6b, 6d, 6f, 6n, 6o, 6t, and 6x significantly decreased the number of blood vessels, and compound 6b was the most effective antiangiogenic agent comparable to dexamethasone. Molecular docking studies were conducted for compound 6b to investigate its mode of interaction within the binding site of both c-Met and VEGFR2 kinases.

Design, Synthesis, and Biological Evaluation of Novel 7H-[1,2,4]Triazolo[3,4-b][1,3,4]thiadiazine Inhibitors as Antitumor Agents.

A series of novel anticancer hydrazinotriazolothiadiazine-based derivatives were designed based on the structure-activity relationship of the previously reported anticancer triazolothiadiazines. These derivatives were synthesized and biologically screened against full NCI-60 cancer cell lines revealing compound 5l with a potential antiproliferative effect. 5l was screened over 16 kinases to study its cytotoxic mechanism which showed to inhibit glycogen synthase kinase-3 ß (GSK-3ß) with IC50 equal to 0.883 µM and 14-fold selectivity over CDK2. Also, 5l increased active caspase-3 levels, induced cell cycle arrest at the G2-M phase, and increased the percentage of Annexin V-fluorescein isothiocyanate-positive apoptotic cells in PC-3 prostate cancer-treated cells. Molecular docking and dynamics were performed to predict the binding mode of 5l in the GSK-3ß ATP binding site. 5l can be utilized as a starting scaffold for developing potential GSK-3ß inhibitors.

Design and novel synthetic approach supported with molecular docking and biological evidence for naphthoquinone-hydrazinotriazolothiadiazine analogs as potential anticancer inhibiting topoisomerase-IIB.

A novel synthetic approach was developed for the synthesis of 3-hydrazinotriazolothiadiazines in just one step from Purpald and phenacyl bromides. They were then selectively tethered to naphthoquinone fragments through hydrazine moiety generating novel Naphthoquinone-hydrazinotriazolothiadiazine analogues. In vitro cytotoxicity for the synthesized chemical entities was validated against HepG2 and MCF-7 cell lines and recorded IC50 inhibitory profile range of 0.07-19.68 µM and 1.19-67.32 µM respectively. Among the synthesized series, compound 4c had maximal cytotoxicity against HepG2 and was therefore selected for further downstream biological investigations. Caspase 3 apoptotic marker was significantly upregulated in cells treated with compound 4c with induction of apoptosis at Pre-G1 phase and cell death at G2/M phase. Compounds 4a, 4c and 4d exhibited the most powerful inhibitory range (0.55-0.64 µM) against Topo IIB. Molecular docking study revealed potential interactions of those compounds within the ATP catalytic binding domain of Topo-IIB with high scores. In conclusion, the novel Naphthoquinone-hydrazinotriazolothiadiazine analogues could serve as promising anticancer agents through inhibition of Topoisomerase-IIB.

Discovery of 5-aryl-3-thiophen-2-yl-1H-pyrazoles as a new class of Hsp90 inhibitors in hepatocellular carcinoma.

Although hepatocellular carcinoma (HCC)-related mortality has increased over the past decades, treatment options are still very limited, underlining the need for developing new therapeutic strategies. The molecular chaperone heat shock protein 90 (Hsp90) plays a key role in post-translational maturation of many oncogenic client proteins that are important for survival and proliferation of cancer cells. Thus, inhibitors of Hsp90 are promising targets for many cancer types. In this study, 15 diarylpyrazole compounds were screened against MCF7 and HepG2 cell lines. Compound 8, which contained a thiophene group, demonstrated the highest antiproliferative activity against HepG2 cells having an IC50 of 0.083 µM. Four additional diarylpyrazoles, each containing a thiophene group, were prepared and screened for antiproliferative activity. None of these four compounds exhibited superior activity to compound 8 on HepG2 cells. Therefore, compound 8 was selected for further in vitro assays. Cell cycle arrest was observed at the G2 phase in compound 8-treated cells. Compound 8 also caused a 7.7-fold increase in caspase-3. These results confirm the apoptotic effect of compound 8 on HepG2 cells. Moreover, compound 8 inhibited Hsp90 (IC50 = 2.67 ±â€¯0.18 µM) in an in vitro assay and caused a 70.8% reduction in Hsp90 levels in a HepG2 cell-based assay. Additionally, compound 8 caused significant reduction in the levels of Hsp90 client proteins (Akt, c-Met, c-Raf, and EGFR) and a 1.57-fold increase in Hsp70. Molecular docking studies were also performed to predict the binding mode of compound 8 and followed by molecular dynamics simulations to give further insights into the binding mode of 8.

Synthesis of Nucleoside-5'-O-Tetraphosphates from Activated Trimetaphosphate and Nucleoside-5'-O-Monophosphates.

This article describes a straight-forward chemical method for the synthesis of nucleoside-5'-O-tetraphosphates, such as cytosine-, guanosine-, adenosine-, and uridine-5'-O-tetraphosphates, starting from the corresponding nucleoside monophosphates and trimetaphosphate, a readily available and inexpensive starting material. The procedure involves reacting the tri(tetrabutylammonium) salt of trimetaphosphate with mesitylenesulfonyl chloride and N-methylimidazole. The resulting activated cyclic trimetaphosphate is reacted with the tetrabutylammonium salts of nucleoside monophosphates. After quenching the reaction with buffer and high-performance liquid chromatography purification, the desired nucleoside-5'-O-tetraphosphates were obtained in yields of 84% to 86%. © 2018 by John Wiley & Sons, Inc.

Efficient One-Pot, Two-Component Modular Synthesis of 3,5-Disubstituted Pyrazoles.

The pyrazole scaffold is one of the most prevalent and important tool in medicinal chemistry. Here, we report a method for preparing 3,5-diarylpyrazoles in good to excellent yield by reacting hydrazones of aryl aldehydes with substituted acetophenones in ethanol in the presence of dimethyl sulfoxide/cat. I2/cat. HCl. The reverse process, reacting hydrazones of substituted acetophenones with aryl aldehydes under the same conditions, also provides 3,5-diarylpyrazoles in good to excellent yields. Reaction of hydrazones of aldehydes with 2'-aryloxy ketones in the presence of cat. HCl in ethanol and the catalyst-free reaction of phenacyl bromides with hydrazones of aldehydes in ethanol also gave good to excellent yields of 3,5-diarylpyrazoles.

Exploring the Potent Inhibition of CTP Synthase by Gemcitabine-5'-Triphosphate.

CTP synthase (CTPS) catalyzes the conversion of UTP to CTP and is a target for the development of antiviral, anticancer, antiprotozoal, and immunosuppressive agents. Exposure of cell lines to the antineoplastic cytidine analogue gemcitabine causes depletion of intracellular CTP levels, but the direct inhibition of CTPS by its metabolite gemcitabine-5'-triphosphate (dF-dCTP) has not been demonstrated. We show that dF-dCTP is a potent competitive inhibitor of Escherichia coli CTPS with respect to UTP [Ki =(3.0±0.1) µm], and that its binding affinity exceeds that of CTP ≈75-fold. Site-directed mutagenesis studies indicated that Glu149 is an important binding determinant for both CTP and dF-dCTP. Comparison of the binding affinities of the 5'-triphosphates of 2'-fluoro-2'-deoxycytidine and 2'-fluoro-2'-deoxyarabinocytidine revealed that the 2'-F-arabino group contributes markedly to the strong binding of dF-dCTP. Geminal 2'-F substitution on UTP (dF-dUTP) did not result in an increase in binding affinity with CTPS. Remarkably, CTPS catalyzed the conversion of dF-dUTP into dF-dCTP, thus suggesting that dF-dCTP might be regenerated in vivo from its catabolite dF-dUTP.

Synthesis of Nucleoside Triphosphates from 2'-3'-Protected Nucleosides Using Trimetaphosphate.

Chemists have been attempting to triphosphorylate nucleosides and other alcohols using trimetaphosphate (TriMP) since the 1960s. However, this route appears to have been abandoned due to poor yields. The first practical syntheses of nucleoside triphosphates (NTPs) are reported using TriMP as the key reagent. This was achieved by reacting the tetrabutylammonium salt of TriMP with mesitylenesulfonyl chloride in the presence of DABCO in pyridine followed by the addition of an appropriately protected nucleoside and phthalimide. Quenching the reaction with aqueous buffer followed by hydrolysis of the OH protecting groups gave the NTPs in good yield.

Enhanced Chromatographic Determination of Nicotine in Human Plasma: Applied to Human Volunteers.

Development of enhanced UPLC-UV method for determination of nicotine in human plasma was achieved on a Symmetry(®) C18 column (100 mm × 2.1 mm, 2.2 µm) applying isocratic elution based on Methanol: Acetonitrile: Phosphate Buffer (pH: 2.7) with the ratio (20:30:50, v/v/v) as a mobile phase. The ultraviolet detector was operated at 260 nm. The mobile phase was pumped through the column at a flow rate of 0.2 mL min(-1). The column temperature was adjusted to 50ºC and the injection volume was 2 µL. Quinine was selected as an internal standard (IS) due to its structure similarity to nicotine having basic pyridine ring to optimize the liquid liquid extraction procedure using diethyl ether coupled with vacuum evaporation at 40°C. Validation parameters for nicotine were found to be acceptable over the concentration range of 2.5-50 ng ml(-1). The application of the proposed method on four healthy human volunteers was approved by the ethical committee. The study was carried out under fasting conditions and the concerned subjects were informed about the objectives and possible risks involved in the study. The proposed method proved to be simple and fast which is a major advantage to analyze large number of samples per day using the accelerated vacuum evaporation technique. The method showed satisfactory data for all the parameters tested within the limits for bioanalytical assays. The lower limit of quantification (LLOQ) permits the application of the method for further pharmacological and clinical studies.

Synthesis of nucleoside 5'-tetraphosphates containing terminal fluorescent labels via activated cyclic trimetaphosphate.

2'-Deoxynucleotide 5'-tetraphosphates in which a fluorescent label is attached to the terminal phosphate are used as key reagents in high-throughput DNA sequencing techniques and in single nucleotide polymorphism typing assays. We demonstrate that this class of compounds can be prepared by reacting fluorophores such as 7-hydroxy-4-methylcoumarin, methylfluorescein, fluorescein and resorufin with an activated form of cyclic trimetaphosphate to give intermediate 11. Reaction of 11 with 2'-deoxynucleoside 5'-monophosphates or a nucleoside 5'-monophosphate gave the target compounds in good yield.

The effect of bisphosphonate acidity on the activity of a thymidylyltransferase.

Thymidylyltransferases (thymidine diphospho pyrophosphorylases) are nucleotidylyltransferases that play key roles in the biosynthesis of carbohydrate components within bacterial cell walls and in the biosynthesis of glycosylated natural products. They catalyze the formation of sugar nucleotides concomitant with the release of pyrophosphate. Protein engineering of thymidylyltransferases has been an approach for the production of a variety of non-physiological sugar nucleotides. In this work, we have explored chemical approaches towards modifying the activity of the thymidylyltransferase (Cps2L) cloned from S. pneumoniae, through the use of chemically synthesized 'activated' nucleoside triphosphates with enhanced leaving groups, or by switching the metal ion co-factor specificity. Within a series of phosphonate-containing nucleoside triphosphate analogues, thymidylyltransferase activity is enhanced based on the acidity of the leaving group and a Brønsted-type analysis indicated that leaving group departure is rate limiting. We have also determined IC50 values for a series of bisphosphonates as inhibitors of thymidylyltransferases. No correlation between the acidity of the inhibitors (pKa) and the magnitude of enzyme inhibition was found.

Synthesis of nucleoside tetraphosphates and dinucleoside pentaphosphates via activation of cyclic trimetaphosphate.

A procedure for the synthesis of dinucleoside 5'-pentaphosphates (Np5N) and nucleoside 5'-tetraphosphates (Np4) is described. The procedure relies on the activation of cyclic trimetaphosphate followed by a reaction with a nucleoside 5'-monophosphate (NMP) to give intermediates of type 3. Reaction of 3 with water or an NMP gives the desired products in yields ranging from 77 to 86%.