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PubMed1992

Research on heterocyclic compounds. XXX. Synthesis and pharmacological activity of 2-methylimidazo[1,2-b]pyridazine-3-carboxylic acids.

A group of ethyl 2-methylimidazo[1,2-b]pyridazine-3-carboxylates were prepared by reaction in anhydrous ethanol of some substituted 3-amino-pyridazines with ethyl 2-chloroacetoacetate. The corresponding carboxylic acids were obtained via alkaline or acid hydrolysis and then tested both in vivo to evaluate their antiinflammatory, analgesic and ulcerogenic actions and in vitro for their ability to inhibit the prostaglandin biosynthesis. The pharmacological results are discussed in terms of both structure-activity relationships and mechanism of action.

Animals↗
PubMed1985

Rigid congeners of arylpyridazinones. IV. Synthesis and activity of derivatives of the new heterocyclic system 9H-indeno[2,1-c]pyridazine.

Representative terms of the new heterocyclic system 9H-indeno[2,1-c]pyridazine have been synthesized. Their antiinflammatory, analgesic and antipyretic activities were evaluated, in order to compare the pharmacological profiles with those of the isomeric series of 5H-indeno[1,2-c]pyridazine previously investigated. The new compounds were, in general, equiactive as analgesic but less active as antiinflammatory and antipyretic agents with respect to their 5H-isomers.

Animals↗
PubMed1979

[3-Hydrazinepyridazine derivatives. III. Synthesis and anti-hypertensive activity of new 3-(2-acylhydrazine)-pyridazine-6-alkylamino substitutes].

The synthesis of 2-(6-dialkylamino-3-pyridazinyl)hydrazinecarboxylates (II) and hydrazides (V) from the corresponding 3-chloro-6-dialkylaminopyridazines (I) is described. The 6-substituted derivatives of 2,3-dihydro-1,2,4-triazolo[4,3-b]pyridazine-3-ones (III) and 1,2,4-triazolo[4,3-b)pyridazines (VI) were obtained by thermal cyclization of (II) and (V), respectively. The new acyl derivatives were evaluated together with todralazine and budralazine as antihypertensive agents in comparison with propildazine and hydralazine. The ethoxycarbonyl compound [(II g), ISF 2469] exhibits good antihypertensive activity particularly via oral administration. Its interesting pharmacodynamic properties, including slow onset and long-lasting action, qualify it for further pharmacological and clinical studies.

Animals↗
PubMed1984

Investigations on derivatives of 5-aminomethyl-6-/p-chloro-phenyl/-4, 5-dihydro-2H-pyridazin-3-one.

Several new derivatives of 5-aminomethyl-6-/p-chlorophenyl/-4, 5-dihydro-2H-pyridazin-3-one have been obtained. The substrates, beta-aminomethyl-beta-/p-chlorobenzoyl/-propionic acid derivatives 1-5, were converted by reactions with hydrazine hydrate or monosubstituted hydrazines, i.e. phenylhydrazine and N-/beta-hydroxyethyl/-hydrazine into appropriate derivatives of 5-aminomethyl-6-/p-chlorophenyl/-4,5-dihydro-2H-pyridazin-3-one 6-18. Compounds 7, 8, 11, 12, 14, 15, and 18 show depressant activity on CNS, while compounds 7a, 9a, 10, 11, 14, 15 possess cytostatic and immunosuppressive activities.

Animals↗
PubMedDate not supplied

[Toxicity and radio-protective properties of pyridazine derivatives].

In experiments in irradiated (CBA X S57B1)F1 mice a study was made of toxicity and radioprotective efficiency of some pyridazine and pyridazine dione derivatives. Some of these substances were shown to have a moderate protective action when administered intraperitoneally. A correlation was revealed between the chemical structure and the radioprotective properties of the compounds.

Animals↗
PubMed1981

[Pharmacological characterization of novel pyridazines. Part 2: Analgetic, antipyretic and antiphlogistic activity (author's transl)].

Using the tail-flick and the hot-plate method as well as the Writhing syndrome as screening procedures, the author tested newly synthetized pyridazine derivatives for analgetic activity in the mouse. Of the 17 compounds tested, the sulphur-containing derivative 3-amino-4-mercapto-6-methylpyridazine (17) has been found to be the most active one. The relatively great effectiveness of 17 was also confirmed in rats (antipyresis model and acute oedema of the hind paw), this substance being superior to all the other compounds under investigation with regard to the quality of the antipyretic and antiphlogistic effects. Further studies of the analgetic, antipyretic and antiphlogistic activity of this group of substances are planned. In this connection, the synthesis of other sulphur-containing pyridazine derivatives seems especially desirable.

Analgesics↗
PubMed1982

[Pharmacological Characterization of novel pyridazines Part 3: Testing on the cardiovascular system and the isolated smooth-muscle organ (author's transl)].

17 newly synthetized pyridazines were tested for activity on the cardiovascular system. Two of them caused a dose dependent fall in blood when applied intravenously. Intravascular administration of one of these two compounds, the hypotensively active hydrazinopyridazine, to the "perfused hind extremities of the rat" gave rise to an increase in flow. All the 17 compounds under investigation were inactive on the isolated ileum preparation. From these results it is concluded that the hypotensive effect of the active pyridazines is attributable to a prominent action on the peripheral vascular system. As all these compounds are regarded as relatively weak, closer examination of their mechanism of action is not planned.

Animals↗
PubMed1980

Cytostatic activity of pyridazine derivatives. I. In vitro studies on 1-methoxyphenylpyridazine-6-ones.

Cytotoxicity of 15 pyridazine derivatives was studied by tissue method on human KB and HeLA cell lines. Six compounds with ED50 activity values between 0.025 and 1.1 micrograms/ml/5.7 X 10(8) - 3.2 X 10(-6) M/were classified for further in vivo investigations. It seems that the halogen in C-5 position plays the main role in the cytotoxic activity of pyridazine-6-ones. The para position of methoxy C-4 group in the lateral benzene ring may be assumed as the next determinant of activity. On the basis of theoretical possibilities a hypothetical model of the role of C-5 halogen substituent in complementary hydrogen bonds with the purines of DNA has been proposed.

Antineoplastic Agents↗
PubMed1995

Research on heterocyclic compounds. XXXIII--Synthesis and analgesic activity of imidazo[1,2-b]pyridazine-2-acetic acid derivatives.

A series of imidazo[1,2-b]pyridazine-2-acetic esters, acids and amides was synthesized and tested for antiinflammatory, analgesic and ulcerogenic activities. The ethyl esters were prepared by cyclocondensation of some 3-aminopyridazines with ethyl 4-chloroacetoacetate, followed by hydrolysis or ammonolysis in order to obtain the corresponding acids and amides. The capacity of inhibiting the carrageenan-induced edema in the rat paw and the writhes induced by acetic acid in mice were evaluated, as well as the ulcerogenic action in rats. The acidic derivatives showed significant analgesic activity which is comparable to that found in other series of imidazo[1,2-b]pyridazine analogs previously examined.

Analgesics↗
PubMed1995

Investigations on the synthesis and properties of some N-arylpiperazinylalkyl derivatives of 1,4-dioxo (1,4,5-trioxo)-1,2,3,4-tetra (and 1,2,3,4,5,6-hexa)hydropyrido[3,4-d]pyridazines.

2-(1-Piperidino)- and 2-(4-methyl-1-piperazinyl)-6-methyl-3, 4-pyridinedicarboximides (1,2) react with CH3NH-NH2 yielding 3-methyl derivatives of the corresponding 1,4-dioxo-1,2,3,4-tetrahydropyrido[3,4-d] pyridazines (4,5). The same reaction with 1,6-dimethyl-2-oxo-1,2-dihydro-3,4- pyridinedicarboximide (3) affords 2-methyl derivative of the corresponding 1,4,5-trioxo-1,2,3,4,5,6- hexahydropyrido[3,4-d]pyridazine (8. Compounds 4,5 and 8 were transformed into their N-arylpiperazinylalkyl derivatives (13-18) on two ways. Some of them were active pharmacologically.

Analgesics↗
PubMed1997

[Antimicrobial activity of new pyridazine derivatives].

Continuing the investigations concerning synthesis-structure-biological activity in the pyridazine series, the results of the antimicrobial and antifungal tests of some new pyridazinium compounds are presented. The test was performed using the diffusimetric method with rustles steel cylinders based on the diffusion of the tested substances on the gelose surface. The comparative analysis of the obtained data leads to the following conclusions concerning the relation between structure and activity in the pyridazine series: 1. The cis-isomers are always more active comparatively with similar trans- isomers: 2. In the pyrrolopyridazine series we remark that the saturated or partial saturated compounds have always a stronger activity as the related aromatics derivatives. We also noticed that the saturated, partial saturated and aromatic compounds have different selectivity. Thus, the saturated are more active on the Pseudomonas aeruginosa and Candida albicans, the partial saturated are more active on the Staphylococcus aureus and Bacillus subtilis while the aromatic compounds are active on the Bacillus subtilis. 3. The influence of the Y-substitutes of para position of benzoylic radical and the substitutes of pyrrolo ring is not decisive towards activity, these affecting especially the selectivity.

Anti-Bacterial Agents↗
PubMedDate not supplied

Synthesis and pharmacological screening of pyrazolo[3,4-c]pyridazine derivatives.

Ethyl 3-chloro-6-(4-chlorophenyl)-pyridazine-4-carboxylate [VII] was cyclized with some nucleophilic reagents (hydrazine hydrate or N-monosubstituted hydrazines) to the new derivatives of pyrazolo[3,4-c]pyridazine [IXa-d]. The structures of the novel compounds were confirmed by elemental and spectral analyses. The effect of several synthesized derivatives on the central nervous system was studied.

Amphetamine↗
PubMedDate not supplied

Pyridazines 82. Synthesis of pyridazino [3,4-b][1,5]benzodiazepin-5-ones and their biological evaluation as non-nucleoside HIV reverse transcriptase inhibitors.

Starting from 3,6-dichloro-N-(2-chloro-5-nitrophenyl)-pyridazine-4-carboxamide (7) a series of 6,11-dialkylated pyridazino- [3,4-b][1,5]benzodiazepin-5-ones with a 3-chloro-8-nitro, 8-amino, 8-acetylamino, or 8-chloro substitution pattern was prepared via N-alkyl-3-alkylamino-6-chloro-N-(2-chloro-5-nitrophenyl) -pyridazine-4-carboxamides. The new compounds were screened as non-nucleoside reverse transcriptase inhibitors. The influence of the substitution pattern in compounds 10-13 on inhibitory potency is discussed.

Anti-HIV Agents↗
PubMed2003

Three- and four-coordinate gold(I) complexes of 3,6-bis(diphenylphosphino)pyridazine: monomers, polymers, and a metallocryptand cage.

The slightly yellow polymeric complexes [Au(2)Cl(2)(P(2)pz)(3)](n), 1 x 6CHCl(3), (P(2)pz is 3,6-bis(diphenylphosphino)pyridazine) and [[Au(2)(P(2)pz)(3)](PF(6))(2)](n), 2, are prepared by the stoichiometric reaction of AuCl(tht) (tht is tetrahydrothiophene) and P(2)pz in either dichloromethane or dichloromethane/methanol, respectively. Addition of 2 equiv of AuCl(tht) to a dichloromethane solution of 1 equiv of P(2)pz generates the simple (AuCl)(2)(P(2)pz) compound, 3. Compound 3 contains nearly linear P-Au-Cl units with intermolecular Au.Au separations of 3.570 A. Au(2)I(2)(P(2)pz)(3), 4, is prepared by reacting excess NaI with 2 in a dichloromethane/methanol mixture. Characterization of 1, 2, and 4 by X-ray crystallography confirms the 2:3 gold/ligand ratio of all three complexes. The coordination polymer 1 maintains a high degree of solvation in the solid-state with three chloroform adducts hydrogen-bonded to the chloride ligand on each gold atom. These chloroform molecules are sandwiched between the two-dimensional polymeric sheets of 1. The crystal structure of 4 reveals an empty, iodide-capped metallocryptand cage with the tetrahedrally distorted gold atoms and the nitrogen atoms on the pyridazine rings directed away from the center of the cavity. No metal ion encapsulation was observed for complex 4. Complex 2 forms one-dimensional arrays of [Au(2)(P(2)pz)(2)](2+) metallomacrocycles connected to each other by a third P(2)pz ligand. The electronic absorption spectra (CH(2)Cl(2)) of 1-4 show broad, nearly featureless absorption bands that tail into the visible with pi-pi bands at 296 nm and discernible shoulders at 314 nm for 2 and 334 nm for 3. Excitation into the low energy band of 2 produces only a modest emission in solution at 540 nm (lambda(ex) 468 nm) and 493 nm (lambda(ex) 403 nm). Under identical conditions, the P(2)pz ligand also emits at 540 and 493 nm.

Journal Article↗
PubMed2003

Synthesis and chemistry of unusual bicyclic endoperoxides containing the pyridazine ring.

Inverse-Diels-Alder reaction of dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate with unsaturated bicyclic endoperoxides gave the bicyclic endoperoxides containing the pyridazine ring. The NEt(3) and CoTPP (TPP = tetraphenylporphyrin) catalyzed reaction of endoperoxide 8 resulted in the formation of hydroxy ketone 11 and cis-diol 9. Cleavage of the peroxide linkage in 8 with thiourea provided cis-diol 9. Oxidation of hydroxy ketone 11 and cis-diol 9 led to the phthalazine-5,8-dione 10. Furthermore, the various transformations of the other endoperoxides 19, 20, 22, 23, and 30 resulted in the formation of pyridazine derivatives.

Journal Article↗
PubMed2005

Synthesis, structure and reactivity of novel pyridazine-coordinated diiron bridging carbene complexes.

[{mu-(Pyridazine-N(1):N(2))}Fe(2)(mu-CO)(CO)(6)](1) reacts with aryllithium reagents, ArLi (Ar = C(6)H(5), m-CH(3)C(6)H(4)) followed by treatment with Me(3)SiCl to give the novel pyridazine-coordinated diiron bridging siloxycarbene complexes [(C(4)H(4)N(2))Fe(2){mu-C(OSiMe(3))Ar}(CO)(6)](2, Ar = C(6)H(5); 3, Ar =m-CH(3)C(6)H(4)). Complex 2 reacts with HBF(4).Et(2)O at low temperature to yield a cationic bridging carbyne complex [(C(4)H(4)N(2))Fe(2)(mu-CC(6)H(5))(CO)(6)]BF(4)(4). Cationic 4 reacts with NaBH(4) in THF at low temperature to afford the diiron bridging arylcarbene complex [(C(4)H(4)N(2))Fe(2){mu-C(H)C(6)H(5)}(CO)(6)](5). Unexpectedly, the reaction of 4 with NaSCH(3) under similar conditions gave the bridging arylcarbene complex 5 and a carbonyl-coordinated diiron bridging carbene complex [Fe(2){mu-C(SCH(3))C(6)H(5)}(CO)(7)](6), while the reaction of NaSC(6)H(4)CH(3)-p with 4 affords the expected bridging arylthiocarbene complex [(C(4)H(4)N(2))Fe(2){mu-C(SC(6)H(4)CH(3)-p)C(6)H(5)}(CO)(6)](7), which can be converted into a novel diiron bridging carbyne complex with a thiolato-bridged ligand, [Fe(2)(mu-CC(6)H(5))(mu-SC(6)H(4)CH(3)-p)(CO)(6)](8). Cationic can also react with the carbonylmetal anionic compound Na(2)[Fe(CO)(4)] to yield complex 5, while the reactions of 4 with carbonylmetal anionic compounds Na[M(CO)(5)(CN)](M = Cr, Mo, W) produce the diiron bridging aryl(pentacarbonylcyanometal)carbene complexes [(C(4)H(4)N(2))Fe(2)-{mu-C(C(6)H(5))NCM(CO)(5)}(CO)(6)](9, M = Cr; 10, M = Mo; 11, M = W). The structures of complexes 2, 5, 6, 8, and 9 have been established by X-ray diffraction studies.

Journal Article↗
PubMed2005

Dimetallic complexes of a structurally versatile pyridazine-containing Schiff-base macrocyclic ligand with pendant pyridine arms.

The new [2 + 2] Schiff-base macrocyclic ligand L2, containing pyridazine head units and pyridine pendant arms, was synthesised as [Ba(II)2L2(ClO4)4(OH2)] 1 from the barium(II) ion templated condensation reaction of 3,6-diformylpyridazine and N1-(2-aminoethyl)-N1-(methylene-2-pyridyl)-ethane-1,2-diamine. Subsequent transmetallation reactions of 1 with copper(II), iron(II) and manganese(II) perchlorates led to the formation of [Cu(II)2L2](ClO4)4.2MeCN 2, [Fe(II)2L2(MeCN)2](ClO4)4 3 and two manganese complexes, 4 and 5, with the same formula, [Mn(II)2L2(MeCN)(OH2)](ClO4)4, but slightly different crystal structures, respectively. Single-crystal X-ray structural analyses reveal the variety of structures which can be supported by L2 in order to meet the coordination environment preferences of the incorporated metal ions. The barium(II) ions in 1 have an irregular ten-coordinate geometry whereas the copper(II) ions in 2 have a square pyramidal geometry and the iron(II) ions in 3 have an octahedral geometry, while in 4 and 5 every manganese(II) ion is seven-coordinate and the environment can be best described as distorted pentagonal bipyramidal. In 1, 4 and 5 the pyridazine moieties bridge the metal centres [Ba(1)...Ba(2) 4.9557(3)A 1; Mn(1)...Mn(2) 4.520(1)A 4; Mn(1)[dot dot dot]Mn(2) 4.3707(8)A 5] but this is not observed in the copper(II) and iron(II) complexes, 2 and 3, in which the metal ions are well separated [Cu(1)...Cu(2) 5.9378(6)A 2; Fe(1)...Fe(2) 5.7407(12)A 3]. In the cyclic voltammogram of [Cu2(II)L2](ClO4)4.2MeCN 2 in MeCN vs. Ag/AgCl two separate reversible one-electron transfer steps are observed [E(1/2)=0.04 V, DeltaE= 0.12 V and E(1/2)= 0.20 V, DeltaE=0.12 V; K(c)=510; in this system E(1/2)(Fc+/Fc)=0.42 V and DeltaE(Fc+/Fc)=0.08 V]. The other complexes cannot be reversibly reduced/oxidised.

Journal Article↗