On triazoles XLIV [1]. synthesis of new ring systems containing imidazo[2′,1′:3,4] [1,2,4] triazolo [1,5- a ]pyrimidine and imidazo[1′,2′:2,3][1,2,4]triazolo[1,5- a ]pyrimidine skeleton (original) (raw)
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International journal of drug delivery technology, 2023
The research in the field of therapeutics is of great importance for reducing human diseases and for the improvement of the quality of human life. Among a wide range of nitrogencontaining heterocycles, 1,2,3-triazole and pyrimidine rings are the most common structural motifs in synthetic and natural bio-active compounds. 1,2 1,2,3-Triazole ring is an aromatic five-membered heterocycle containing two carbon atoms and three nitrogen atoms located at 1-,2-,3-positions. 3,4 Synthetically, 1,2,3-triazole ring system is easily constructed via 1,3-dipolar cycloaddition reactions of organic azides with alkynes or activated alkenes under different conditions to give regioselective 1,4-disubstitued-1,2,3-triazole derivatives. 5-8 Characteristically, 1,2,3-triazole ring system is amide bond isosteres to be resistance the biological degradation, 9 stable towards chemical hydrolysis, oxidative and reductive conditions. 4 Moreover, 1,2,3-triazole ring system can form interactions via hydrogen bonding Vander-Waals forces, π-π stacking interactions and dipole-dipole bonds with a variety of receptors such as enzymes, proteins and nucleic acids. 10,11 Thus, compounds contain 1,2,3-triazole ring system showing a broad range of pharmaceutical applications such as antioxidant, 12 anticancer, 13 antimicrobial, 14 antiviral, 15 antibacterial 16 and antidiabetic agents. 17,18 On the other hand, pyrimidine ring (1,3-diazine) is an aromatic six-membered heterocycle with two nitrogen atoms located at 1-and 3-positions and alloxan (5,5-dihydroxypyrimidine-2,4,6(1H,3H,5H)-trione) is the first pyrimidine derivative was isolated in 1818 via oxidizing of uric acid with nitric acid. 19 Characteristically, pyrimidine ring is a weak base (pKa 1.31) and has a high dipole moment that subtends π-π stacking interactions with dual hydrogen-bonding capacity that can be of importance in drug-target interactions and is normally stable towards ringopening reactions. 20 Many efficient synthetic approaches for synthesizing compounds containing pyrimidine ring or its derivatives have been developed and reported. 21,22 However, the reaction of α, β-unsaturated ketones (Chalcones) with urea under acidic or basic conditions is an excellent illustrative method to produce the corresponding 2-pyrimidinone ring. 23,24 Pyrimidine motif and its derivatives are privileged fragments in drug discovery with a wide range of medical applications for example; antioxidant 25 anticancer, 26 antiviral, 27 and antiinflammatory. 28 Given the above, combining 1,2,3-triazole and pyrimidine motifs in the same matrix was interesting to introduce new compounds with two active sites for potential antiviral applications.
On triazoles. VII Synthesis of novel tri‐ and tetracyclic ring systems
Journal of Heterocyclic Chemistry, 1987
The ring‐closure of the 5‐amino‐1‐(2‐aminophenyl)‐3‐methylthio‐1H‐1,2,4‐triazole derivatives 3 and 4 with different simple and cyclic C1 components lead to the formation of 1,2,4‐triazolo[1,5‐α]‐1,3,5‐benzotriazepines 5–6, their 4,5‐dihydro‐ 7, different 5‐spiro‐homocyclic‐ 8–13, and 5‐spiro‐heterocyclic‐ 14‐15 analogues. The structure of the compounds obtained was proved with the use of their ir, uv, 1H‐nmr and 13C‐nmr spectra.
Synthesis of [1,2,3]triazolo-[4',5':4,5]pyrimido[1,6-a]benzimidazole, a new heterocyclic system
Chemistry of Heterocyclic Compounds, 2009
Benzimidazole derivatives are used in medicine as antiulcer, antihypertonic, antivirus, antifungal, antineoplastic, antihistaminic, and anthelmintic agents [1]. Biological activity is also found for imidazo[1,2-a]pyrimidine [4-9] and triazolo[4,5-d]pyrimidine . In the present work, we propose a convenient method for the synthesis of a new polynuclear system, namely, [1,2,3]triazolo[4',5':4,5]pyrimido-[1,6-a]benzimidazole, in which the above-mentioned fragments are combined.
Novel Synthesis of (R)-Imidazolo[1,2c][1,2,3]triazolo[4,5e]pyrimidines
Asian Journal of Chemistry
Heterocyclic compounds are broadly distributed in nature, in the form of amino acids, triazoles, pyrimidines and purines. Simple substituted triazoles have biological activities such as antifungal 3,4 , antiinflammatory andanalgesic 4 , antiviral 5 , antimalarial 6 , etc. Triazoles are also widely used in industrial applications such as dyes, photostabillizers, photographic materials and agrochemicals 7. Likewise, pyrimidine derivatives also exhibit biological activities such as anticancer 8 , antibacterial 9 , antiviral 10 , antifungal 8 , antiinflammatory 11 , etc. Among the fused heterocyclics, triazolo-pyrimidines represent a pharmaceutically important class of compounds because of their different biological activities, such as antiviral 12 , antifungal 13 , anticancer 14 , antitumer 13,15,16 , antituberculosis 17 , anti-HIV 18,19 , cytotoxicity 20. In addition, they have been found to be present in DNA-interactive agents. Herein we wish to report the synthesis of some fused triazolopyrimidine derivatives having one chiral center which may potentially be biologically active and also as new chemical entities. EXPERIMENTAL Unless stated otherwise, reactions were performed under nitrogen atmosphere. Reactions were monitored by thin layer Novel Synthesis of (R)-Imidazolo[1,2c][1,2,3]triazolo[4,5e]pyrimidines
Journal of Molecular Structure, 2000
4,5-Dihydro-5-oxo-[1,2,4]triazolo-[1,5-a]pyrimidine (5HtpO) and 4,7-dihydro-7-oxo-[1,2,4]triazolo-[1,5-a]pyrimidine (7HtpO) have been synthesized by the condensation of 3-amino-[1,2,4]triazole with a reagent bearing the three carbon atoms that close the six-membered ring in a strongly acidic (7HtpO) or strongly basic (5HtpO) medium. The crystal structures of these compounds have been determined by X-ray diffraction, exhibiting the N4-H tautomer, as expected from the RHF/AM1 calculations. The different possibilities for binding metal ions are discussed from the MO results. ᭧
Journal of Molecular Structure, 2011
Novel [1,2,4]-triazolo-[1,5-a]pyrimidine derivatives were prepared by oxidative cyclization of suitable Nbenzylidene-N 0 -pyrimidin-2-yl hydrazine precursors, followed by a Dimroth rearrangement. Reaction of 6-bromo-[1,2,4]-triazolo-[4,3-a]pyrimidines with aliphatic amines under microwave irradiation gave the unexpected 5-amino compounds from an ANRORC-type mechanism. Full NMR and HRMS characterization was done for all the obtained compounds. DFT calculations of absolute shielding permitted to predict 1 H, 13 C and 15 N chemical shifts, which were in good agreement with the experimental ones. Theoretical studies at the B3LYP/6-311++G(d,p) level corroborated that [1,2,4]-triazolo-[1,5-a]pyrimidines were more stable than their [4,3-a] counterparts.
HETEROCYCLES, 2000
Substituted 3-amino-4-oxo-4H-pyridino[1,2-α]pyrimidines (6, 7), available in 2 steps from methyl 2-benzyloxycarbonylamino-3-dimethylaminopropenoate (3) and 2-aminopyridines (1, 2), were diazotized into stable diazonium tetrafluoroborates (8, 9). Heating of diazonium salts (8, 9) with primary alcohols furnished alkyl 1-(substituted pyridin-2-yl)-1H-1,2,3-triazoles (11, 12) in 30-70% yields. Quinolizines 1 and their 1-aza analogs, pyridino[1,2-α]pyimidines, 2 are constituents of various naturally occurring alkaloids exhibiting neuroleptic 3 analgesic, 4 antiemetic, 5 antibacterial, 6 and antitumor activity. 7 On the other hand, 1,2,3-triazoles and fused 1,2,3-triazoles also represent an important class of heterocyclic compounds which have found a wide and versatile use in organic synthesis, medicinal chemistry, and industrial applications. 8 For example, 1H-1,2,3-benzotriazole is a highly efficient synthetic auxiliary 9 and numerous 1,2,3-triazole derivatives exhibit diverse biological activities, such as antiviral, 10 fungicidal, 11 muscarinic, 12 antiallergic, 13 anticoccidial, 14 anti-HIV-1, 15 antiepileptic, 16 antiinflammatory, 17 prostaglandin synthesis inhibition, 18 and others. 19 Recently, 2-substituted 3-(dimethylamino)propenoates proved to be simple and efficient reagents for the preparation of various heterocyclic systems. 20,21 For example, 3-substituted 4-oxo-4H-pyridino[1,2-]pyrimidines can be prepared in one step from 2-aminopyridines and 2-substituted 3-(dimethylamino)propenoates. 20-23 Utilization of 2-benzyloxycarbonylamino and 2-vinylamino substituted 3-(dimethylamino)propenoates made 3-amino-4-oxo-4H-pyridino[1,2-]pyrimidines available in two steps and good yields from 2-aminopyridine derivatives. 22,23 In continuation of our research in this field we studied transformations of 3-amino-4-oxo-4H-pyridino[1,2
Monatshefte für Chemie - Chemical Monthly, 2008
A series of new N-and S-substituted 1,3,4-oxadiazole derivatives were synthesized. 5-Pyridin-3-yl-3-[2-(5-thioxo-4,5-dihydro-l,3,4-thiadiazol-2-yl)ethyl]-1,3,4-oxadiazole-2(3H)-thione and 5-[(5-(pyridin-3-yl)-1,3,4-oxadiazol-2-ylthio)methyl]-Nphenyl-1,3,4-thiadiazol-2-amine were formed by cyclization of 3-(5-pyridin-3-yl-2-thioxo-1,3,4-oxadiazol-3(2H)-ylpropanimidohydrazide and 2-[(5-pyridin-3-yl-1,3,4-oxadiazol-2-yl)thio]thiosemicarbazide with CS 2 and H 2 SO 4 . On the other hand, a number of new bicyclic 1,2,4-triazolo[3,4-b][1,3,4]thiadiazole derivatives were synthesized. 6-Pyridin-3-ylbis[1,2,4]triazolo[3,4-b:4 0 ,3 0 -d][1,3,4]thiadiazole-3(2H)-thione was synthesized by reaction of 6-(hydrazino)-3-pyridine-3-yl[1,2,4]triazolo [3,4-b][1,3,4]thiadiazole with CS 2 =KOH=EtOH. The structures of the newly synthesized compounds were elucidated by the spectral and analytical data IR, Mass, and 1 H NMR spectra.