Search

The utilization of arylhydrazononitriles (6-9) for synthesis of azoles is demonstrated. Thus, arylazomalononitriles (6) reacted with hydroxylamine hydrochloride to afford isoxazol-5-imine (10), amidoxime (12) and bis-amidoxime (13) derivatives depending upon both the reaction conditions and molar ratio employed. 2-Thiazolyl-2-arylhydrazononitriles (7) and cyanoformazans (8) gave 1,2,3-triazole derivatives (15) and (17) respectively upon treatment with hydroxylamine hydrochloride and concomitant loss of water molecule. Formation of novel 1,2,4-triazin-5(4H)-one derivatives (21) has efficiently been carried out by treatment of amidoximes (18) with acetic anhydride in acetic acid.

Arylhydrazononitriles react with hydroxylamine hydrochloride in refluxing ethanolic sodium acetate to yield amidoximes that cyclized into 1,2,3-triazol-5-amines or 1,2,4-triazol-5-amines depending on the nature of the substituents on hydrazone linkage. NOE difference experiments could successfully be utilized to distinguish 1,2,3-triazoles from isomeric 1,2,4-triazoles.

A series of thiazoles (III) and (V), 1,3-thiazines (IX), and thiazolidine (VII) is prepared in the presence of an environmentally friendly basic chitosan-grafted-poly(vinylpyridine) catalyst.

A novel synthesis of a series of pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5-ones has been developed from reactions of 1-(5-methyl-1-phenyl-1H-pyrazol-4-yl)-3-arylprop-2-en-1-ones and 7-amino-1,3-disubstituted[1,2,4]triazolo[4,3-a]pyrimidin-5(1H)-ones in dioxane under thermal conditions, using cellulose sulfuric acid as an eco-friendly acid catalyst. The reaction mechanism was proposed and the structures of the newly synthesized compounds were established on the basis of spectral data (mass spectrometry, infrared, 1H and 13C nuclear magnetic resonance) and elemental analyses.

The reaction between 3-amino-2,3-dihydro-7,9-dimethyl-2-thioxo-pyrido[3′,2′:4,5]thieno[3,2-d]-pyrimidin-4(1H)-one 4 or its 2-methylthio derivative 5 with hydrazonoyl halides 6 in dioxane in the presence of triethylamine under reflux has followed heterocyclization reaction to yield pyrido[3″,2″:4′,5′]-thieno[3′,2′:4,5]pyrimido[2,1-c][1,2,4,5]tetrazin-6(4H)-ones 9. On the other hand, reaction of compound 4 with hydrazonoyl halides 6 in sodium ethoxide at room temperature led to formation of hydrazonothioate compounds 10. The latter on treatment with glacial acetic acid produced tetracyclic compounds, namely 2-arylhydrazonopyrido[3″,2″:4′,5′]thieno [3′,2′:4,5]pyrimido[2,1-b][1,3,4]thiadiazinones 11. An alternative method was carried out to prove the structure of product 11. The mechanism of the reaction under study was proposed and the products were screened for their biological activity.

Two series of 7-arylazo-7H-3-(2-methyl-1H-indol-3-yl)pyrazolo[5,1-c][1,2,4]triazol-6(5H)-ones 4 and 7-arylhydrazono-7H-3-(2-methyl-1H-indol-3-yl)-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazines 7 were prepared via reactions of 4-amino-3-mercapto-5-(2-methyl-1H-indol-3-yl)-1,2,4-triazole 1 with ethyl arylhydrazono-chloroacetate 2 and N-aryl-2-oxoalkanehydrazonoyl halides 5, respectively. A possible mechanism is proposed to account for the formation of the products. The biological activity of some of these products was also evaluated.

Treatment of 6-hydroxy-5-phenylazo-2-thioxo-4(1H)-pyrimidinone 1 with a series of hydrazonoyl halides 2 and N,2-diaryl-diazinecarbohydrazonoyl halides 9 in dioxane in the presence of triethylamine under reflux furnishes 6-phenylazo and 3,6-bis(arylazo)-7-hydroxy-1H-[1,2,4]triazolo[4,3-a]pyrimidin-5(4H)-one derivatives 7 and 10, respectively. The biological activities of the products were evaluated.

Electrochemical fluorination of 2-alkylthio-4-methyloxazoles has been successfully carried out using Et4NF·nHF (n=4, 5) as the supporting electrolyte and fluoride source to provide the corresponding 2-alkylthio-4,5-difluoro-4-methyl-2-oxazolines, and fluorination did not take place at α to the sulfur atom. In the case of electrochemical fluorination of 2-methylthio-4-cabomethoxyoxazole afforded a 2,5-difluoro-3-oxazoline derivative in addition to a 4,5-difluoro-2-oxazoline one. In contrast, anodic fluorination of 2,4,5-trimethyloxazole devoid of a thio group resulted in no formation of fluorinated products.

Aryl propargyl sulfides were subjected to electrochemical fluorination in dimethoxyethane (DME) containing various fluoride supporting electrolytes using an undivided cell to provide the corresponding α-monofluorinated or α,α-difluorinated sulfides selectively as main products in good yields depending on the amount of electricity passed. The α,α-difluorinated sulfides were stable enough to be isolated while the α-monofluorinated ones were very unstable. The α-monofluorinated sulfides were readily converted into the corresponding stable α-monofluoroallenyl sulfides in good yields. Furthermore, synthetic utility of α-monofluoroallenyl sulfides was also investigated.

A simple one-pot method is reported for the synthesis of several novel series of chromeno[4′,3′:4,5]pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidine-6,14-diones, chromeno[4′,3′:4,5]pyr­ido[2,3-d]thiazolo[3,2-a]pyrimidine-6,14-diones, and chrom-­eno[4′′,3′′:4′,5′]pyrido[2′,3′:4,5]pyrimido[2,1-b][1,3]thiazine-6,15-dione by a multicomponent reaction of salicylaldehyde, ethyl acetoacetate, and the appropriate fused heterocyclic amines in refluxing glacial acetic acid. The structures of the newly synthesized compounds were established by spectroscopy and elemental analyses. The mechanism of the single-step reaction was elucidated.

A series of title compounds of type (III), (IV), (VI), (VIII), or (X) are prepared and tested for their antibacterial and antifungal activities.

Anodic fluorination of various nitrogen-containing heterocyclic propargyl sulfides using Et4NF·nHF (n=3,4) or Et3N·3HF as a supporting electrolyte and fluoride ion source in dimethoxyethane provided the corresponding monofluorinated products in moderate yields. Fluorination took place selectively at the position α to the sulfur atom of the sulfides and the heterocyclic moieties were not fluorinated at all.

A series of pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-5-ones (8) has been synthesised via reaction of 5-substituted-2-thioxo-2,3-dihydro-1H-pyrido[2,3-d]pyrimidin-4-one (3) or its methylthio derivative 4 with hydrazonoyl chlorides 5. Alternative syntheses of products 8 were carried out either by reaction of enaminone 1 with 7-amino-1,3-disubstituted[1,2,4]triazolo[4,3-a]pyrimidin-5-one (10) or via the Japp-Klingemann reaction of compound 13. Both conventional thermal and microwave irradiation techniques were used for synthesis of the target products 8 and a comparative study of these techniques using triethylamine or chitosan, as basic catalysts, was carried out. The mechanisms of the reactions under investigation are discussed. In addition, the antimicrobial activity of the newly synthesized products was evaluated.

Pyrrole derivative (I) is used as starting material for a series of title compounds of type (III), (V), (VII), and (XI).

A variety of new thiazoles and thiazines bearing an imidazole moiety are synthesized using ethylidenethiosemicarbazide (I) as starting material.

Purpose: To carry out a neat synthesis of 2-amino-5,6-dihydro-8-methoxy-4-phenylbenzo[h]quinoline-3- carbonitrile (compound 2 ) and 2-amino-5,6-dihydro-8-methoxy-4-phenyl-4H-benzo[h]chromene-3- carbonitrile (compound 3 ) and evaluate their cytotoxic activity in human glioblastoma cells. Methods: Benzo[h]quinoline and benzo[h]chromene were synthesized by treating 6-methoxy-1- tetralone with benzylidenemalononitrile under microwave irradiation. The structures of compounds 2 and 3 were confirmed by elemental, spectral, and x-ray crystallographic analyses. The cytotoxic activity of compounds 2 and 3 was evaluated using WST-1 assay in U373 human glioblastoma cell line. Results: The molecular structures of compounds 2 and 3 were demonstrated unambiguously from single crystal x-ray measurements and they crystallized in triclinic form, P-1, for both compounds. In vitro cytotoxic activity data for compound 2 in human glioblastoma cell line (U373) indicate that no significant cytotoxicity was observed. On the other hand, compound 3 showed highly significant cytotoxic effects on U373 cells at concentrations starting from 0.1 μg/ mL. Conclusion: Compound 3 produces a decrease in cell viability with approximately 80 % cell death while compound 2 did not indicate significant cytotoxic activity. This suggests that the chromene moiety of compound 3 may be responsible for its high cytotoxicity. Keywords: Hydronaphthaline, Benzo[h]quinolone, Benzo[h]chromene, X-ray crystallography, U373 human glioblastoma, Cytotoxicity, Chromene moiety

The anodic fluorination of aryl propargyl sulfides in DME containing a fluoride supporting electrolyte using an undivided cell provided the corresponding α-mono- and α,α-difluorinated sulfides selectively, depending on the amount of electricity passed. The α-monofluorinated sulfides were readily converted into the corresponding α-fluoroallenyl sulfides in good to moderate yields.

The acid dissociation constants (Ka) of a series of 3,4-diaryl-1H-1,2,4-triazole-5-thiones (1) were determined and were found to correlated linearly with Hammett substituent constants; log Ka = 1.06 σx − 11.01. Such a result indicates that 1 exists essentially in one tautomeric form namely the thione form. Reactions of 1 with hydrazonoyl chlorides 2 gave the thiohydrazides 5. Similiar reaction of 3-phenyl-1H(4H)- 1,2,4-triazole-5-thione 1g with 2a gave the thiohydrazide 5h which was converted into 1,3,5-triphenyl-1,2,4-triazolo[3,4-c]-1,2,4-triazole (9). The latter was also prepared from 3-phenyl-5-methylthio-4H-1,2,4-triazole (6) and 2a. The mechanism of the reaction of 1 with 2 is discussed.

Three series of novel pyrazole derivatives 2b-d, 4a-d and 6a-d were synthesized via two step procedure that utilizes hydrazonoyl chlorides 1a-d and enaminones 3a-d and 5a-d, respectively as starting materials. The structures of all the newly synthesized products have been established on the basis of analytical and spectral data. Moreover, some of the products 2-6 were tested against HCV and Subacute Sclerosing Panencephalitis (SSPE). In addition, compounds 2-6 were also tested for the inhibition of peroxynitrite-induced tyrosine nitration and antioxidant activity. The tested compounds are highly effective at very low concentration as anti-HCV, SSPE antioxidant and anticancer in the following ascending order 2d, 4c, 6b, 3b, 6c, 4d, 2b, 2c, 2a, 6a, 5b, 5a, 3a, 4b and 5c. It is worth to mention that all tested compounds are more potent than the reference standards used for comparing activity. All the measurements revealed that the mechanism of action of the anti cancer activities of all the tested compounds is topoisomerase I inhibitor.

The anodic fluorination of aryl propargyl sulfides in DME containing a fluoride supporting electrolyte using an undivided cell provided the corresponding α-mono- and α,α-difluorinated sulfides selectively, depending on the amount of electricity passed. The α-monofluorinated sulfides were readily converted into the corresponding α-fluoroallenyl sulfides in good to moderate yields.

Anodic fluorination of various nitrogen-containing heterocyclic propargyl sulfides using Et4NF·nHF (n=3,4) or Et3N·3HF as a supporting electrolyte and fluoride ion source in dimethoxyethane provided the corresponding monofluorinated products in moderate yields. Fluorination took place selectively at the position α to the sulfur atom of the sulfides and the heterocyclic moieties were not fluorinated at all.

Aryl propargyl sulfides were subjected to electrochemical fluorination in dimethoxyethane (DME) containing various fluoride supporting electrolytes using an undivided cell to provide the corresponding α-monofluorinated or α,α-difluorinated sulfides selectively as main products in good yields depending on the amount of electricity passed. The α,α-difluorinated sulfides were stable enough to be isolated while the α-monofluorinated ones were very unstable. The α-monofluorinated sulfides were readily converted into the corresponding stable α-monofluoroallenyl sulfides in good yields. Furthermore, synthetic utility of α-monofluoroallenyl sulfides was also investigated.

Three series of novel pyrazole derivatives 2b-d, 4a-d and 6a-d were synthesized via two step procedure that utilizes hydrazonoyl chlorides 1a-d and enaminones 3a-d and 5a-d, respectively as starting materials. The structures of all the newly synthesized products have been established on the basis of analytical and spectral data. Moreover, some of the products 2-6 were tested against HCV and Subacute Sclerosing Panencephalitis (SSPE). In addition, compounds 2-6 were also tested for the inhibition of peroxynitrite-induced tyrosine nitration and antioxidant activity. The tested compounds are highly effective at very low concentration as anti-HCV, SSPE antioxidant and anticancer in the following ascending order 2d, 4c, 6b, 3b, 6c, 4d, 2b, 2c, 2a, 6a, 5b, 5a, 3a, 4b and 5c. It is worth to mention that all tested compounds are more potent than the reference standards used for comparing activity. All the measurements revealed that the mechanism of action of the anti cancer activities of all the tested compounds is topoisomerase I inhibitor.

Recent synthesis and utilization of enamines as precursors for heterocyclic and carbocyclic compounds are reviewed. Two general synthetic routes for preparation of enamines based on condensation and addition reactions. Enamines and azaenamines can be used as building blocks for carbocyclic, five-and six-membered heterocyclic as well as fused heterocyclic compounds.

The utilization of arylhydrazononitriles (6-9) for synthesis of azoles is demonstrated. Thus, arylazomalononitriles (6) reacted with hydroxylamine hydrochloride to afford isoxazol-5-imine (10), amidoxime (12) and bis-amidoxime (13) derivatives depending upon both the reaction conditions and molar ratio employed. 2-Thiazolyl-2-arylhydrazononitriles (7) and cyanoformazans (8) gave 1,2,3-triazole derivatives (15) and (17) respectively upon treatment with hydroxylamine hydrochloride and concomitant loss of water molecule. Formation of novel 1,2,4-triazin-5(4H)-one derivatives (21) has efficiently been carried out by treatment of amidoximes (18) with acetic anhydride in acetic acid.

Reactions of arene and heteroaromatics diazonium salts with active methylene compounds having cyano group have been illustrated to afford hydrazonoalkanenitriles with a range of substituents. Structural investigation for hydrazonoalkanenitriles has been made. Furthermore the reactivity of hyrazonoalkanenitriles towards nucleophilic and electrophilic reagents has been displayed.

In the presence of triethylamine, cycloaddition reaction of enamine 1 with hydrazonoyl halides 2 followed by dimethylamine elimination was achieved, yielding the corresponding 1,3,4-trisubstituted pyrazoles 4. Coupling of enamine 1 with aromatic diazonium salts afforded 2-(arylhydrazono)-2-(4-nitrophenyl)acetaldehyde 9 in good yield. Refluxing the phenyl hydrazone 9a with chloroacetone in ethanol in the presence of triethylamine afforded 1,3,5-trisubstituted pyrazole 12a, formed via intermediate 11a. Reaction of 9a with hydroxylamine hydrochloride in ethanol in the presence of anhydrous sodium acetate yielded oxime 13a which was irradiated in a microwave oven in the presence of acetic acid to afford a mixture of 15a and 16a.

Reaction of 3, 3'-bis(4-phenyl-1,2, 4-triazole-5-thione) 1 with hydrazonoyl halides 2 in ethanol in the presence of sodium ethoxide affords directly the thiohydrazides 4, via in situ rearrangement of the initially formed thiohydrazonate esters 3. The involvement of the latter was evidenced by an alternate synthesis of 4.

In a typical embedded laser-based acquisition system, real-time 3D image computation may be affected by several main factors, like processor speed, complexity of re-mapping functions, the size of the 3D image and the correctness of optical data (artifact correction). To achieve the desired performance, the designer may choose a fully hardware-based solution. However, this will increase the system cost. In this paper, we propose a hardware-software system design framework based on a DSP processor, and look-up tables (LUT) to compute a 3D image in real-time and achieve the desired throughput

The anodic fluorination of 2-thiazolyl methyl sulfide, 2-thiazolyl propargyl sulfide, and 2-thiazolyl acetonyl sulfide was successfully carried out to provide the corresponding 5-fluorothiazole and 2,5,5-trifluorothiazoline derivatives. The latter products were readily hydrolyzed to give isolable 5,5-difluoro-2-hydroxythiazoline derivatives. On the other hand, anodic fluorination of 2-thiazolyl cyanomethyl sulfide afforded 5-fluorothiazole and alpha-fluorinated thiazole derivatives. Thus, the product selectivity was found to be greatly changed by the electron-withdrawing ability of substituents at the side chain of the thiazole ring. This is the first report of a successful anodic fluorination of a thiazole ring.

Working within the framework of the Coulomb-modified Glauber model, we instead of conventionally using the Gaussian approximation to the basic input nucleon–nucleon (NN) amplitude, evaluate it from a three-parameter phenomenological NN phase shift function. At a given projectile energy the parameters of the NN phase shift function are varied to fit the α–nucleus elastic-scattering data. It is found that once the parameters of the NN phase shift function are fixed, it very nicely reproduces the available elastic α–scattering data on other nuclei at the same energy. By applying this procedure, a reasonably good account of elastic-scattering data for α–40–48Ca,58Ni,116Sn and 208Pb have been achieved in the energy range about 0.2 GeV–1.37 GeV.