In silico Design, Synthesis and Biological Evaluation of Novel Thieno[3,2-d]pyrimidine Derivatives for Cancer Therapy - A Preliminary Study on the Inhibitory Potential towards ATR Kinase Domain and PIKK Family

Continuing our studies in the field of new heterocyclic compounds with biological interest, herein we report the synthesis and anticancer activity of new N- and S-substituted derivatives of tetracyclic pyrido[3',2' : 4,5]thieno[3,2-d]pyrimidines. In this regard, starting from the thieno[2,3-b]pyridine-2-carboxylates, the corresponding 8(9)-aminopyrido[3',2' : 4,5]thieno[3,2-d]pyrimidin-7(8)-ones, as well as chloro derivatives were obtained. Based on the latter, amino, hydrazino and S-alkyl derivatives of pyrido[3',2' : 4,5]thieno[3,2-d]pyrimidines were synthesized subsequently. The current study focuses on identifying the potential of thieno[3,2-d]pyrimidine derivatives primarily towards ATR kinase inhibition, through computational predictions, followed by synthesis and cancer cell viability studies, along with an aim to develop the core as PIKK inhibitors for cancer therapy.

New Bicyclic Pyridine-Based Hybrids Linked to the 1,2,3-Triazole Unit: Synthesis via Click Reaction and Evaluation of Neurotropic Activity and Molecular Docking

The synthesis of new original bicyclic pyridine-based hybrids linked to the 1,2,3-triazole unit was described via a click reaction. The anticonvulsant activity and some psychotropic properties of the new compounds were evaluated. The biological assays demonstrated that some of the studied compounds showed high anticonvulsant and psychotropic properties. The five most active compounds (7a, d, g, j, and m) contain a pyrano [3,4-c]pyridine cycle with a methyl group in the pyridine ring in their structures. Furthermore, molecular docking studies were performed, and their results are in agreement with experimental data.

Synthesis of 1-Amino-3-oxo-2,7-naphthyridines via Smiles Rearrangement: A New Approach in the Field of Chemistry of Heterocyclic Compounds

In this paper we describe an efficient method for the synthesis of new heterocyclic systems: furo[2,3-c]-2,7-naphthyridines 6, as well as a new method for the preparation of 1,3-diamino-2,7-naphthyridines 11. For the first time, a Smiles rearrangement was carried out in the 2,7-naphthyridine series, thus gaining the opportunity to synthesize 1-amino-3-oxo-2,7-naphthyridines 4, which are the starting compounds for obtaining furo[2,3-c]-2,7-naphthyridines. The cyclization of alkoxyacetamides 9 proceeds via two different processes: the expected formation of furo[2,3-c]-2,7-naphthyridines 10 and the ‘unexpected’ formation of 1,3-diamino-2,7-naphthyridines 11 (via a Smiles type rearrangement).

A Study of the Regiochemistry in the Synthesis of Pyrano[3,4-c]pyridines

Aims:

Biological studies have shown that some condensed derivatives of pyrano[3,4- c]pyridines 6 exhibited pronounced biological activity. Considering these results, the principal aim of this work is to study the regiochemistry of the synthesis of pyrano[3,4-c]pyridines 6, to optimize the reaction conditions and thus to increase the previously observed low yields of pyrano[ 3,4-c]pyridines.

Background:

Within this research line, some of us, several years ago, developed a method for the preparation of 6-oxopyrano[3,4-c]pyridines 6 starting from 2,2-dimethyltetrahydro-4Hpyran- 4-one 1. In these studies, we separated and identified only the most expected reaction products 6-oxopyrano[3,4-c]pyridines 6. On the basis of this datum, we suggested that the enamines 2 and 3, reacting with acyl chlorides, were not acylated at C-3 and that 5-acylpyran-4- ones 4 were the only products of the reaction. We have justified this result by considering the steric effects exerted by the two methyl groups present in the pyran ring. Moreover, we did not identify the products at the second reaction center: that is, the isomeric compounds 7 and this result was justified considering the different reactivity of aliphatic and cyclic ketone groups.

Objectives:

The main objectives of this work were:

• implementation of the reaction of 2,2-dimethyltetrahydro-4H-pyran-4-one 1 with morpholine;

• acylation of the obtained enamines 2 and 3 with acyl chlorides under Stork conditions;

• synthesis of pyranopyridines 6-8 based on β-diketones: 3-acylpyran-4-ones 4 and 5-acylpyran-4-ones 5;

• confirmation of the structure of the obtained compounds.

Methods:

For the synthesis of pyrano[3,4-c]pyridines known methods were used. Thus, the reaction of starting 2,2- dimethyltetrahydro-4H-pyran-4-one 1 with morpholine in benzene led to the formation of isomeric enamines 2 and 3. After, they were acylated with acyl chlorides under Stork conditions with formation of two β -diketones: 3- acylpyran-4-ones 4 and 5-acylpyran-4-ones 5. Finally, in order to obtain the aimed pyrano[3,4-c]pyridines 6, the obtained β-dicarbonyl compounds 4 and 5 (as a mixture of isomers) were reacted with 2-cyanoacetamide in ethanol in the presence of diethylamine, according to the Knoevenagel condensation. The structure of the obtained compounds has been unambiguously confirmed by using a wide spectrum of physico-chemical methods (NMR, IR, Xray structural and elemental analysis) and, in the instance of compounds 7, also by an alternative synthesis.

Results:

Starting from the 2,2-dimethyltetrahydro-4H-pyran-4-one 1 a series of new and already known 6- oxopyrano[3,4-c]pyridines 6 were synthesized. As a result of the study of the regiochemistry in the synthesis of pyrano[3,4-c]pyridines, of the four possible isomer pyranopyridines 6-9, we have succeeded in identifying three of them (6-8). Thus, isomer pyranopyridines 7 and 8 were identified in the mixture with the main compounds 6. Moreover, isomeric pyrano[3,4-c]pyridines 8 were detected when alkyl groups are present in the starting compounds 4 and 5, while isomeric pyrano[4,3-b]pyridines 7 were detected in the case of the presence of aromatic groups. Unfortunately, we have not been able to isolate compounds 7 and 8 in the pure state from the reaction mixtures. At now, we have not been able to detect and identify isomeric pyrano[4,3-b]pyridines 9. On the whole, we have been able to better the effectiveness of the synthesis of pyrano[3,4-c]pyridines 6, increasing their yields by ≈ 5-15%.

Conclusion:

As a result of our investigation, we have found that the acylation reaction of enamines 2 and 3 and the cyclization reaction of β-diketones 4 and 5 are not regioselective. Therefore, we can state that enamines 2 and 3 can be acylated at both C-3 and C-5 with the formation of a mixture of 3-acylpyran-4-ones 4 and of 5-acylpyran-4-ones 5. Their condensation with 2-cyanoacetamide led to the formation of mixtures of regioisomeric pyranopyridines 6- 8. In conclusion, as a result of our present research, we can say that we have been able to increase the effectiveness of the synthesis of pyranopyridines, largely improving our previous results.

Other:

Now, we are working to look for the fourth isomeric pyrano[4,3-b]pyridines 9 by using the most modern and fine methods. Moreover, we hope that we shall be able to separate the mixtures of pyranopyridines 6-8: any way they can be used for further syntheses as they are.

Synthesis of 3,3-dimethyl-6-oxopyrano[3,4-c]pyridines and their antiplatelet and vasodilatory activity

OBJECTIVES

Both pyridine and pyrano derivatives have been previously shown to possess biologically relevant activity. In this study, we report the incorporation of these two scaffolds into one molecule.

METHODS

The designed 3,3-dimethyl-6-oxopyrano[3,4-c]pyridines were synthesized by the acylation of enamine under Stork conditions followed by condensation of formed β-diketones with 2-cyanoacetamide. The structures of these compounds were confirmed by using a wide spectrum of physico-chemical methods. Their antiplatelet, anticoagulant and vasodilatory activity together with toxicity were evaluated.

KEY FINDINGS

A series of 6-oxopyrano[3,4-c]pyridines 3a-j was obtained. Four of these compounds were reported for the first time. None of the tested compounds demonstrated anticoagulant effect but 8-methyl derivative (3a) was a potent antiplatelet compound with IC50 numerically twice as low as the clinically used acetylsalicylic acid. A series of further mechanistic tests showed that 3a interferes with calcium signaling. The compound is also not toxic and in addition possesses vasodilatory activity as well.

CONCLUSIONS

Compound 3a is a promising inhibitor of platelet aggregation, whose mechanism of action should be studied in detail.

Synthesis and Neurotropic Activity of New Heterocyclic Systems: Pyridofuro[3,2-d]pyrrolo[1,2-a]pyrimidines, Pyridofuro[3,2-d]pyrido[1,2-a]pyrimidines and Pyridofuro[3',2':4,5]pyrimido[1,2-a]azepines

Background: Neurotic disturbances, anxiety, neurosis-like disorders, and stress situations are widespread. Benzodiazepine tranquillizers have been found to be among the most effective antianxiety drugs. The pharmacological action of benzodiazepines is due to their interaction with the supra-molecular membrane GABA-a-benzodiazepine receptor complex, linked to the Cl-ionophore. Benzodiazepines enhance GABA-ergic transmission and this has led to a study of the role of GABA in anxiety. The search for anxiolytics and anticonvulsive agents has involved glutamate-ergic, 5HT-ergic substances and neuropeptides. However, each of these well-known anxiolytics, anticonvulsants and cognition enhancers (nootropics) has repeatedly been reported to have many adverse side effects, therefore there is an urgent need to search for new drugs able to restore damaged cognitive functions without causing significant adverse reactions. Objective: Considering the relevance of epilepsy diffusion in the world, we have addressed our attention to the discovery of new drugs in this field Thus our aim is the synthesis and study of new compounds with antiepileptic (anticonvulsant) and not only, activity. Methods: For the synthesis of compounds classical organic methods were used and developed. For the evaluation of biological activity some anticonvulsant and psychotropic methods were used. Results: As a result of multistep reactions 26 new, five-membered heterocyclic systems were obtained. PASS prediction of anticonvulsant activity was performed for the whole set of the designed molecules and probability to be active Pa values were ranging from 0.275 to 0.43. The studied compounds exhibit protection against pentylenetetrazole (PTZ) seizures, anti-thiosemicarbazides effect as well as some psychotropic effect. The biological assays evidenced that some of the studied compounds showed a high anticonvulsant activity by antagonism with pentylenetetrazole. The toxicity of compounds is low and they do not induce muscle relaxation in the studied doses. According to the study of psychotropic activity it was found that the selected compounds have an activating behavior and anxiolytic effects on the models of “open field” and “elevated plus maze” (EPM). The data obtained indicate the anxiolytic (anti-anxiety) activity of the derivatives of pyrimidines, especially pronounced in compounds 6n, 6b, and 7c. The studied compounds increase the latent time of first immobilization on the model of “forced swimming” (FST) and exhibit some antidepressant effect similarly to diazepam. Docking studies revealed that compound 6k bound tightly in the active site of GABA_A receptor with a value of the scoring function that estimates free energy of binding (ΔG) at −7.95 kcal/mol, while compound 6n showed the best docking score and seems to be dual inhibitor of SERT transporter as well as 5-HT_1A receptor. Conclusions: Тhe selected compounds have an anticonvulsant, activating behavior and anxiolytic effects, at the same time exhibit some antidepressant effect.

Pyridofuropyrrolo[1,2-a]pyrimidines and pyridofuropyrimido[1,2-a]azepines: new chemical entities (NCE) with anticonvulsive and psychotropic properties

A series of pyridofuropyrrolo[1,2-a]pyrimidines4and of pyridofuropyrimido[1,2-a]azepines5having as precursors a some new condensed furo[2,3-b]pyridines3were synthesized and evaluated for their anticonvulsive and psychotropic properties.

Pyridofuropyrrolo[1,2-a]pyrimidines and pyridofuropyrimido[1,2-a]azepines: new chemical entities (NCE) with anticonvulsive and psychotropic properties

A series of pyridofuropyrrolo[1,2-a]pyrimidines4and pyridofuropyrimido[1,2-a]azepines5, with new condensed furo[2,3-b]pyridines3as precursors, were synthesized and evaluated for their anticonvulsive and psychotropic properties.