Aryldiazonium Chlorides Research Articles

Regioselective Radical Arylation of 3-Hydroxypyridines.

The titanium(III)-mediated radical arylation of 3-hydroxypyridines was found to proceed with high regioselectivity for the 2-position. Using aryldiazonium chlorides, which were prepared from the corresponding anilines, as aryl radical sources, a range of 3-hydroxy-2-phenylpyridines were obtained in moderate to good yields under simple reaction conditions. Reactions of ortho-carboxylic ester substituted phenyldiazonium salts directly provided tricyclic benzopyranopyridinones.

Synthesis and anti-depressant evaluation of novel pyrazolone derivatives

<p class="Abstract">Diazotization of substituted anilines with NaNO<sub>2</sub> and concentrated hydro-chloric acid at 0ºC gave the diazonium chlorides. Coupling of substituted aryl diazonium chlorides with ethyl acetoacetate in methanol gave ethyl-2-aryl-hydrazono-3-oxobutyrates (2a-h). Reaction of (2a-h) with naphthoic carbohydrazide (3) gave the title compounds pyrazolone derivatives (4a-h). The newly synthesized compounds were screened for their in vivo anti-depressant activity by tail suspension test and forced swimming test. Some of the tested compounds 4f, 4g showed very good activity when compared to the standard drug imipramine. The newly synthesized compounds were characterized by physical parameters and the structures were elucidated by spectral data.</p><p><strong>Video Clips</strong></p><p><a href="https://www.youtube.com/v/TZtb2a5u4CU">Forced swimming test</a>: 12 min 19 sec</p><p><a href="https://www.youtube.com/v/92mFRfBJgBw">Tail suspension test</a>: 8 min 5 sec</p><p> </p>

PH triggered smart organogel from DCDHF-Hydrazone molecular switch

The design, synthesis and photophysical properties of a Low Molecular Weight pH-responsive Gelator (LMWG) based on alkoxy group functionalized DCDHF-Hydrazones (DCDHF-H) are described. A straightforward synthesis of DCDHF-Hydrazone (DCDHF-H) chromophores was achieved via simple azo-coupling starting from 2-(dicyanomethylene)-2,5-dihydro-4,5,5-trimethylfuran-3-carbonitrile and alkoxy bearing aryl diazonium chloride derivatives. The DCDHF-H efficiently gelate selected organic solvents and reversibly respond to pH stimuli with a gel-sol conversion and an associated color change from yellow to purple. Self-assembly of these molecules, as indicated by X-ray crystallography, occurs via cooperative π–π stacking and van der Waals interactions producing gelation in some pure and mixed organic solvents. Furthermore, the presence of acidic or alkaline gases leads to a dramatic change in the rheological properties with potential applications in areas such as gas detection devices and drug release systems. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies of the xerogels obtained from n-propanol provide visual images revealing the formation of fibrous nanostructures.

Ultrasound Assisted Synthesis of Some Novel Bis‐Pyridazine Derivatives

Bis‐enaminone 3 was coupled with aryldiazonium chlorides 4a, 4b to afford the bis‐arylhydrazonopropanals 6a, 6b. Compounds 6a, 6b could be utilized for the synthesis of a variety of bis‐(dimethyl 2,3‐dihydropyridazine‐3,4‐dicarboxylate), bis‐(pyridazin‐3(2H)‐one), bis‐(2,3‐dihydropyridazine‐4‐carbonitrile) and bis‐(3‐imino‐2,3‐dihydropyridazine) derivatives, under ultrasonic irradiation. A comparative study of aforementioned reactions was carried out under conventional method as well as under ultrasonic irradiation conditions.

Synthesis and anticancer activity of some new heterocyclic compounds based on 1-cyanoacetyl-3,5-dimethylpyrazole

The starting 3-(3,5-dimethyl-1H-pyrazol-1-yl)-3-oxopropanenitrile (1) reacts with phenyl isothiocyanate and ethyl bromoacetate to give the corresponding thiazole derivative 4. On repetition of the reaction using phenacyl bromides 5a–d (instead of ethyl bromoacetate), oxathiepine-6-carbonitriles 10a–d were obtained. Coupling of compound 1 with aryldiazonium chlorides gives the corresponding 2-(arylhydrazono)-(3,5-dimethyl-1H-pyrazol-1-yl)-3-oxopropanenitrile derivatives 12a–e, which on treatment with p-phenylenediamine, followed by reaction of hydrazine hydrate afforded pyrazole derivatives 15a–d. The reaction of 1 with 5-amino-3-(cyanomethyl)-1H-pyrazole-4-carbonitrile afforded the respective 2-cyanomethyl-pyrazolo[1,5-a]pyrimidine-3-carbonitrile derivative 18. Compound 18 reacted with phenyl isothiocyanate in the presence of potassium hydroxide at room temperature and then phenacyl bromide was added; the pyrazolopyrimidines 24 were obtained. The structures of all the newly synthesized products were confirmed based on elemental, spectral data and a plausible mechanism has been postulated to account for their formation. Also, we evaluate the anticancer activity of some representative examples of the newly synthesized compounds.

ChemInform Abstract: Conversion of Aromatic Amino into Trifluoromethyl Groups Through a Sandmeyer‐Type Transformation.

A novel strategy for aromatic trifluoromethylation by converting amino into trifluoromethyl groups via a Sandmeyer-type reaction is reported. The transformation involves diazotization of the aromatic amines with tert-butyl nitrite and hydrochloric acid to form aryldiazonium chlorides, followed by trifluoromethylation with trifluoromethylsilver at low temperature. Various readily available aromatic amines are smoothly converted under mild conditions.

Conversion of Aromatic Amino into Trifluoromethyl Groups through a Sandmeyer­-Type Transformation

A novel strategy for aromatic trifluoromethylation by converting amino into trifluoromethyl groups via a Sandmeyer-type reaction is reported. The transformation involves diazotization of the aromatic amines with tert-butyl nitrite and hydrochloric acid to form aryldiazonium chlorides, followed by trifluoromethylation with trifluoromethylsilver at low temperature. Various readily available aromatic amines are smoothly converted under mild conditions.

ChemInform Abstract: Synthesis of 1,4,5‐Trisubstituted‐1,2,3‐triazoles via Coupling Reaction of Diaminomaleonitrile with Aromatic Diazonium Salts.

AbstractThe reactions of aryldiazonium chlorides with diaminodicyanoethylene (I) are examined with respect to the formation of 1,2,3‐triazoles.

Efficient synthesis of some new functionalized 3-amino- and 5-aminopyrazoles derivatives

Cyanoacetic acid hydrazide derivatives were utilized as key intermediates for the synthesis of some new 3-amino- and 5-aminopyrazole derivatives. Coupling of N′-phenylsulfonyl-2-cyanoacetohydrazide (1) and 1-(2-cyanoacetyl)-4-phenyl thiosemicarbazide (4) with different aryl diazonium chlorides afforded the corresponding 5-amino-1-substituted-4-pyrazolin-3-one derivatives 3 and 6, respectively. Treatment of ketene dithioacetal 9 and ketene-N,S-acetal 13 with hydrazine and/or benzenesulfonyl hydrazide furnished the corresponding 3-amino-5-1H-pyrazole-4-carbohydrazide derivatives 10, 11, and 14. The structures of the new synthesized compounds were elucidated and confirmed by elemental analyses and spectral data.

DIPYRROLO[1,2- a ;2',1'- c ]PYRAZINES. 5. AZO COUPLING OF DIPYRROLO[1,2- a ;2',1'- c ]PYRAZINES AND 5,6-DIHYDRODIPYRROLO[1,2- a ;2',1'- c ]PYRAZINES

We have synthesized a series of previously unreported azo dyes via the azo coupling of alkyl substituted dipyrrolopyrazines with aryldiazonium chloride. For this type of substrate where one or both α-positions of the pyrrole rings of the molecules are not occupied by substituents, electrophilic attack was found to occur initially at carbon atom C(3). Authors: V. I. Terenin, A. V. Borisov, E. L. Ruchkina, and A. P. Pleshkova. English Translation in Chemistry of Heterocyclic Compounds , 1999, 35 (2), pp 211-215 http://link.springer.com/article/10.1007/BF02251713

NEW APPROACHES FOR THE SYNTHESIS AND ANTITUMOR EVALUATION OF PYRIDINE, THIENO[3,4-c]PYRIDINE, PYRAZOLO[3,4-b]PYRIDINE AND PYRIDO[3,4-d]PYRIDAZINE DERIVATIVES

This work has been carried out to investigate the utility of arylidene acetoacetanilides 3a, b in heterocyclic synthesis. Thus the synthesis of pyridine derivatives 6a, b , 8a-d , 12a, b were done by the reaction of arylidine derivatives 3a,b with activated methylene groups 4a, b , also synthesis of compounds 15 , 21a , b , 22a , b were carried out via the reaction of compound 12a with benzaldehyde (2a) and reaction of arylidine derivatives 3a,b with ethylcyanoacetate (4b) in addition to reaction of compound 21a with either benzaldehyde (2a) or salicylaldehyde (2c) respectively. Isoquinoline derivative 14 was afforded via the reaction of compound 12a with malononitrile (4a) . Thieno[3,4- c ]pyridine derivatives 10 , 19 were afforded via the reaction of 2-pyridone derivatives either 8a or 12a with elemental sulphur respectively , pyrazolo[3,4- b ]pyridine drivatives 18a, b were synthesized through the reaction of compound 12a with either hydrazine hydrate or phenylhydrazine 16a , b. Finally pyrido[3,4- d ]pyridazine derivatives 25a, b . were produced via the reaction between compound 21a and aryldiazonium chlorides 23a , b . The biological potentialities of the prepared compounds has been examined and evaluated as antitumor agents. All compounds showed significant growth inhibitory effect.

Synthesis and Fungicidal Activity of Novel 3-(Substituted/unsubstituted phenylselenonyl)-1-ribosyl/deoxyribosyl-1H-1,2,4-triazole

Reaction of potassium 1H-1,2,4-triazole-3-selenolate (I) with acetylated ribose/deoxyribose (IIa,b) in the presence of montmorillonite K 10 as a solid adsorbent furnished potassium 1-acetylated ribosyl/deoxyribosyl-1H-1,2,4-triazole-3-selenolate (IIIa,b) with excellent yield under microwave irradiation in solvent-free conditions. This eliminates a series of complex isolation procedures and often minimizes the use of a large amount of expensive, toxic, and hazardous solvents after each step. This procedure reduces reaction time and cost and enhances yield. Reaction of compound (IIIa,b) with substituted/unsubstituted aryl diazonium chloride (IVa-e) at 0-5 °C gave pure 3-(substituted/unsubstituted phenyl selanyl)-1-acetylribosyl/deoxyribosyl-1H-1,2,4-triazole (Va-j). Oxidation of compound (Va-j) with oxone followed by alkaline hydrolysis furnished quantitatively and analytically pure 3-(substituted/unsubstituted phenylselenonyl)-1-ribosyl/deoxyribosyl-1H-1,2,4-triazole (VIIa-j). Compounds VIa-j and VIIa-j were evaluated in vitro for their fungitoxicities against Fusarium oxysporum and Penicillium citrinum. All the compounds were found to be antifungal active. Some of the compounds displayed activities comparable with that of the commercial fungicide Dithane M-45 and griseofulvin. Structure-activity relationships for the screened compounds were discussed. The fact that both of these fungi have developed resistance to several fungicide groups made them optimal candidates as target organisms for ongoing research about the potential application of 1,2,4-triazole and analogue compounds as reduced-risk fungicides.

In vitro antimicrobial and antitubercular studies of novel 6-substituted (pyrrolidin-1-yl)-2(1H)-pyridinones

A series of 6-amino-substituted pyridine-2-(1H)-ones have been prepared by coupling of substituted 6-(pyrrolidin-1-yl)-2(1H)-pyridinones with aryl diazonium chlorides. The overall sequence provides a simple and efficient route to prepare 6-amino-substituted pyridine-2-(1H)-ones in the form of two isomers, which were separated using column chromatography. The structure of all the compounds has been assigned unambiguously on the basis of elemental analysis, IR and NMR spectral data and has been evaluated for antibacterial and antifungal activities. The active compounds were evaluated for antitubercular activity and compared with standard drug rifampicin.

Synthesis of novel 6-(substituted amino)-4-(4-ethoxyphenyl)-1-phenyl-2(1H)-pyridinones via azo coupling

6-(Substituted amino)-4-(4-ethoxyphenyl)-1-phenyl-2(1H)-pyridinones were prepared from β-aryl glutaconic acid, which, on fusion with aniline, results in 4-(4-ethoxyphenyl)-1-phenylpyridine-2,6(1H,5H)-dione. This, on further treatment with phosphorus oxychloride gave 6-chloro-4-(4-ethoxyphenyl)-1-phenyl-2(1H)-pyridinone, and further treatment with secondary amines yielded 6-(substituted amino)-4-(4-ethoxyphenyl)-1-phenyl-2(1H)-pyridinones. These were subjected to azo coupling with different aryldiazonium chlorides furnishing two isomers, which were separated by column chromatography. All compounds were characterized by elemental analysis, and use of IR and NMR spectral data, and were evaluated for antimicrobial activity.

New arylhydrazonothiazolidin-5-one disperse dyes for dyeing polyester fibers

New arylhydrazonothiazolidin-5-one disperse dyes for dyeing polyester fibers A series of new thiazolidin-5-one disperse dyes was synthesized from the reactions of 2-substituted 3-phenylthiazolidinones with various aryldiazonium chlorides. The synthesized dyes were characterized by UV-visible absorption, IR, NMR and MS spectroscopy. The dyes gave orange to reddish-violet shades with very good depth on polyester fibers. The dyed fabrics show moderate to good fastness to light and very good to excellent fastness to washing and perspiration. Also, the assessment of color coordinates was discussed.

Synthesis of some new Indeno[1,2-e]pyrazolo[5,1-c]-1,2,4-triazin-6-one and Indeno[2,1-c]pyridazine-4-carbonitrile Derivatives

Diazonium chlorides of 5-amino-3-methypyrazole 1a and 5-amino-4-phenylpyrazole 1b coupled with 1,3-indanedione 2 and led to the formation of acyclic hydrazone 3a and a cyclic product indenopyrazolotriazine 4b respectively. Cyclization of the hydrazone 3a by boiling in acetic acid afforded the corresponding 4a. The hydrazone 3a reacted with malononitrile in boiling ethanol in the presence of piperidine and gave indeno[2,1-c]pyridazine-4-carbonitrile derivatives 5a,b. Also, coupling of 6 with aryl diazonium chlorides gave the corresponding indenopyridazine derivatives 8a-e. Acetylation, benzoylation and hydrolysis of compound 8a afforded the corresponding substitution products 10-12, respectively. The structures of the newly synthesized compounds were established on the basis of chemical and spectral evidences.

Synthesis and anion binding of 2-arylazo-meso-octamethylcalix[4]pyrroles

2-Arylazo-5,5,10,10,15,15,20,20-octamethylcalix[4]pyrroles (azo-OMCPs) have been synthesised by the reaction of calix[4]pyrrole with aryldiazonium chloride in 15–45% yields. The solution-state binding studies of the synthesised hosts were investigated by absorption spectroscopy and 1H NMR in DMSO and CDCl3, respectively. These receptors, appended with electron-donating and electron-withdrawing groups, displayed enhanced affinity and selectivity for fluoride anion. Well-defined colour change in the visible region of the spectrum was observed upon addition of fluoride ion in DMSO solution of azo-OMCPs. Detailed NMR studies in CDCl3 revealed that azo-OMCPs with nitro and chloro groups have higher binding affinity for fluoride ion.

Synthesis and Antimicrobial Activity of Some New Formazan Derivatives

A series of new substituted formazan derivatives has been synthesized from corresponding aryl diazonium chloride and Schiff base in pyridine. The synthesized compounds were identified by spectral studies and screened for their antimicrobial activities.

Synthesis of annulated dihydroisoquinoline heterocycles via their nitrogen ylides

3,4-Dihydro-6,7-dimethoxyisoquinoline-1-acetonitrile reacts with some α-bromoketones in dry benzene to give the corresponding isoquinolinium salts, which undergo intramolecular cyclization to give pyrrolo[2,1- a]isoquinolines. Cross-coupling of the latter compounds with some aryldiazonium chlorides resulted in the formation of 3-arylhydrazonopyrrolo[2,1- a]isoquinolines, 3-arylazopyrrolo[2,1- a]isoquinolines and 3-aryl-1,2,3-triazolo[5,1- a]isoquinolines, respectively. The structures of the products were established on the basis of their elemental and spectral analyses as well as X-ray single crystal studies.

Enantiomerically pure organoseleno-1-arylethanols by enzymatic resolution with Candida antarctica lipase: Novozym 435

Racemic organoseleno-1-arylethanols were prepared by ortho-lithiation of arylethanols, followed by sequential reaction with elemental selenium and alkyl halides and by reaction of either aryldiazonium chlorides with diphenyldiselenide or with lithium and magnesium alkylselenolates. Enantiomerically enriched organoseleno-1-arylethanols were obtained by kinetic resolution of the racemic mixtures by esterification catalyzed by Candida antarctica lipase (Novozym 435). In some cases, enantiomeric excesses of up to 99% were obtained both for alcohols and acetates.