Synthesis of 4‐(1‐phenyl‐1H‐pyrazol‐3‐yl)‐[1,2,4]triazolo[4,3‐a]quinoxalines and their 4‐halogenopyrazolyl analogs

Synthesis of {3‐[1‐(ethoxycarbonyl)‐[1,2,4]triazolo[4,3‐a]quinoxalin‐4‐yl]‐1‐phenyl‐1H‐pyrazol‐5‐yl}methyl ethyl oxalate ( 2 ), ethyl 4‐[5‐(acetoxymethyl)‐1‐phenyl‐1H‐pyrazol‐3‐yl]‐[1,2,4]triazolo[4,3‐a]quioxaline‐1‐carboxylate ( 4 ), [4‐halo‐1‐phenyl‐3‐(1‐phenyl‐[1,2,4]triazolo[4,3‐a]quioxalin‐4‐yl)‐1H‐pyrazol‐5‐yl]methyl acetate ( 11 ), {4‐halo‐3‐[1‐methyl‐[1,2,4]triazolo[4,3‐a]quinoxalin‐4‐yl]‐1‐phenyl‐1H‐pyraz‐ol‐5‐yl}methyl acetate ( 13 ), and [3‐([1,2,4]triazolo‐[4,3‐a]quinoxalin‐4‐yl)‐4‐halo‐1‐phenyl‐1H‐pyrazol‐5‐yl] methyl formate ( 15 ) was accomplished. The structural investigation of the new compounds is based on chemical and spectroscopic evidences. J. Heterocyclic Chem., (2011)     

2‐Triazolylpyrimido[1,2,3‐cd]purine‐8,10‐diones via 1,3‐dipolar cycloadditions to 2‐ethynylpyrimido[1,2,3‐cd]purine‐8,10‐dione

This paper presents the synthesis of a series of 5,6‐dihydro‐4H,8H‐pyrimido[1,2,3‐cd]purine‐8,10(9H)‐dione ring system derivatives with a [1,2,3]triazole ring bonded in position 2. The procedure is based on cycloaddition of substituted alkyl azides to the terminal triple bond of 5,6‐dihydro‐2‐ethynyl‐9‐methyl‐4H,8H‐pyrimido[1,2,3‐cd]purine‐8,10(9H)‐dione ( 4 ). This cycloaddition produced two regioisomers ?5,6‐dihydro‐9‐methyl‐2‐(1‐substituted‐1H‐[1,2,3]triazol‐5‐yl)‐4H,8H‐pyrimido[1,2,3‐cd]purine‐8,10(9H)‐dione ( 7 ) and 2‐(1‐substituted‐1H‐[1,2,3]triazol‐4‐yl) derivative 8 . The required 2‐ethynyl deriva tive 4 was obtained from the starting 2‐unsubstituted compound 1 by bromination to yield the 2‐bromo derivative 2 , which was converted by Sonogashira reaction to trimethylsilylethyne 3 and finally, the protective trimethylsilyl group was removed by hydrolysis.     

Synthesis and Biological Activities of 7‐Arylazo‐7H‐pyrazolo[5,1‐c][1,2,4] Triazol‐6(5H)‐Ones and 7‐Arylhydrazono‐7H‐[1,2,4]triazolo[3,4‐b] [1,3,4]thiadiazines

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.     

3/4‐phenylene bisheterocycles from ring transformation reaction of sydnone derivatives: Synthesis of 3‐[3/4‐heterocyclyl]phenyl‐5‐methyl‐3H‐[1,3,4]‐oxadiazol‐2‐ones from 3/4‐acetylphenylsydnones and their biological properties

The bifunctional 3/4‐[acetyl]phenylsydnones 1a, 1b were subjected to a one‐pot ring conversion to 3‐[3/4‐acetyl]phenyl‐5‐methyl‐3H‐[1,3,4]‐oxadiazol‐2‐ones 2a, 2b , which on further bromination yielded the 3‐[3/4‐bromoacyl]phenyl‐5‐methyl‐3H‐[1,3,4]‐oxadiazol‐2‐ones 3a, 3b . Reaction of these compounds with thiourea yielded the 3‐[3/4‐(2‐aminothiazol‐4‐yl)]phenyl‐5‐methyl‐3H‐[1,3,4]‐oxadiazol‐2‐ones 4a, 4b . The other thiazole derivatives 5a, 5b–7a, 7b were prepared by using thiosemicarbazide, thioacetamide, and thiobenzamide, respectively. In another reaction of the bromoacetyl compounds ( 3a, 3b ) with 2‐aminopyridine and 2‐aminothiazole, the fused biheterocyclic compounds 3‐[3/4‐imidazo‐[1,2‐a]pyridine‐2‐yl]phenyl‐5‐methyl‐3H‐[1,3,4]‐oxadiazol‐2‐ones 8a, 8b and 3‐[3/4‐imidazo‐[2,1‐b]‐thiazol‐6‐yl]phenyl‐5‐methyl‐3H‐[1,3,4]‐oxadiazol‐2‐ones 9a, 9b were obtained. The 3‐[3/4‐(benzofuran‐2‐carbonyl)]phenyl‐5‐methyl‐3H‐[1,3,4]‐oxadiazol‐2‐ones 10a, 10b were obtained by treatment of compounds 3a, 3b with o‐hydroxy benzaldehyde. Most of these compounds exhibited antifungal activity greater than the reference drugs used. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:50–54, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20255     

Four NiII complexes with the new cyclam–methylimidazole ligand 1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane

Although it has not proved possible to crystallize the newly prepared cyclam–methylimidazole ligand 1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane (L^Im1), the trans and cis isomers of an Ni^II complex, namely trans‐aqua{1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane}nickel(II) bis(perchlorate) monohydrate, [Ni(C₁₅H₃₀N₆)(H₂O)](ClO₄)₂·H₂O, (1), and cis‐aqua{1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane}nickel(II) bis(perchlorate), [Ni(C₁₅H₃₀N₆)(H₂O)](ClO₄)₂, (2), have been prepared and structurally characterized. At different stages of the crystallization and thermal treatment from which (1) and (2) were obtained, a further two compounds were isolated in crystalline form and their structures also analysed, namely trans‐{1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane}(perchlorato)nickel(II) perchlorate, [Ni(ClO₄)(C₁₅H₃₀N₆)]ClO₄, (3), and cis‐{1,8‐bis[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane}nickel(II) bis(perchlorate) 0.24‐hydrate, [Ni(C₂₀H₃₆N₆)](ClO₄)₂·0.24H₂O, (4); the 1,8‐bis[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane ligand is a minor side product, probably formed in trace amounts in the synthesis of L^Im1. The configurations of the cyclam macrocycles in the complexes have been analysed and the structures are compared with analogues from the literature.     

Synthesis and reactions of 11H‐benzo[b]pyrano[3,2‐f]indolizines an pyrrolo[3,2,1‐ij]pyrano[3,2‐c]quinolines

2‐Methyl‐3H‐indoles 1 cyclize with two equivalents of ethyl malonate 2 to form 4‐hydroxy‐11H‐benzo[b]pyrano[3,2‐f]indolizin‐2,5‐diones 3, whereas 2‐mefhyl‐2,3‐dihydro‐1H‐indoles 9 give under similar conditions regioisomer 8‐hydroxy‐5‐methyl‐4,5‐dihydro‐pyrrolo[3,2,1‐ij]pyrano[3,2‐c]quinolin‐7,10‐diones 10 . The pyrone rings of 3 and 9 can be cleaved either by alkaline hydrolysis to give 7‐acetyl‐8‐hydroxy‐10H‐pyrido[1,2‐a]indol‐6‐ones 4 or 5‐acetyl‐6‐hydroxy‐2‐methyl‐1,2‐dihydro‐4H‐pyrrolo‐[3,2,1‐ij]quinolin‐4‐ones 11 , respectively. Chlorination of 3 and 9 with sulfurylchloride gives under subsequent ring opening 7‐dichloroacetyl‐8‐hydroxy‐10H‐pyrido[1,2‐a]indol‐6‐ones 5 or 5‐dichloracetyl‐6‐hydroxy‐2‐methyl‐1,2‐dihydro‐4H‐pyrrolo[3,2,1‐ij]quinolin‐4‐ones 12 . The dichloroacetyl group of 5 can be reduced with zinc to 7‐acetyl‐8‐hydroxy‐10H‐pyrido[1,2‐a]indol‐6‐ones 7. Treatment of the acetyl compounds 4, 7 and 11 with 90% sulfuric acid cleaves the acetyl group and yields 8‐hydroxy‐10H‐pyrido[1,2‐a]‐indol‐6‐ones 6 and 8 , and 6‐hydroxy‐2‐methyl‐1,2‐dihydro‐4H‐pyrrolo[3,2,1‐ij]quinolin‐4‐ones 13 . Reaction of dichloroacetyl compounds 12 with sodium azide yields 6‐hydroxy‐2‐methyl‐5‐(1H‐tetrazol‐5‐ylcarbonyl)‐1,2‐dihydro‐4H‐pyrrolo[3,2,1‐ij]quinolin‐4‐ones 14 via intermediate geminal diazides.     

Syntheses of N‐[3‐(1‐methyl‐1H‐2‐imidazolyl)propyl]benzamides and N‐[3‐(1‐methyl‐1H‐2‐imidazolyl)propyl]benzenesulfonamides

A series of substituted N‐(4‐substituted‐benzoyl)‐N‐[3‐(1‐methyl‐1H‐imidazol‐2‐yl)propyl]amines ( 13 ) and N‐arylsulfonyl‐N‐[3‐(1‐methyl‐1H‐imidazol‐2‐yl)propyl]amines ( 14 ) were prepared from the reaction of 3‐(1‐methyl‐1H‐imidazol‐2‐yl)propan‐1‐amine ( 7 ) with substituted benzoyl chloride or substituted‐benzene sulfonyl chloride respectively. Compound 7 was prepared by two independent methods.     

Synthesis of N1‐substituted coumarino[4,3‐c] pyrazoles

3‐Acyl‐4‐hydroxy‐2‐oxo‐2H‐chromen derivatives 1a‐d were condensed with (7‐hydroxy‐2‐oxo‐2H‐chromen‐4‐yl)‐acetic acid hydrazide 2 , (4‐methyl‐2‐oxo‐2H‐chromen‐7‐yloxy)‐acetic acid hydrazide 3 , and (7‐hydrazinocarbonylmethoxy‐2‐oxo‐2H‐chromen‐4‐yl)‐acetic acid hydrazide 4 , to give corresponding 3‐alkyl‐1‐[2‐(7‐hydroxy‐2‐oxo‐2H‐chromeno‐4‐yl)‐acetyl]‐1H‐chromeno[4,3‐c]pyrazole‐4‐one 5a‐d , 3‐alkyl‐1‐[2‐(4‐methyl‐2‐oxo‐2H‐chromeno‐7‐yloxy)‐acetyl]‐1H‐chromeno[4,3‐c]pyrazole‐4‐one 6a‐d , and 1‐{4‐[(3‐alkyl‐1H‐chromeno[4,3‐c]pyrazole‐4‐one‐1‐yl)‐carbonylmethyl]‐2‐oxo‐2H‐chromen‐7‐yloxy‐acetyl}‐3‐alkyl‐1H‐chromeno[4,3‐c]pyrazole‐4‐one 7a‐d.     

Synthesis of 10‐Aryl‐10H‐naphtho[1,8a,8‐fg]indazol‐7‐ones

3‐Hydroxy‐2‐[1‐(arylhydrazono)ethyl]‐1H‐phenalen‐1‐ones 3 , obtained from 2‐acetyl‐3‐hydroxy‐1H‐phenalen‐1‐one ( 1 ) and arylhydrazines 2 , cyclize under acidic conditions to 8‐methyl‐10‐aryl‐10H‐naphtho‐[1,8a,8‐fg]indazol‐7‐ones 4 . Indazoles 4 are also obtained from 2‐acetyl‐3‐hydroxy‐1H‐phenalen‐1‐one ( 1 ) and arylhydrazines 2 in a one‐pot reaction. 2‐Acetyl‐3‐azido‐1H‐phenalen‐1‐one ( 6 ) does not give 8‐methyl‐9‐arylamino‐9H‐naphtho[1,8a,8‐fg]indazol‐7‐ones via azide decomposition but gives again by nucleophilic replacement of the azide moiety in 6 the indazole 4 .     

Synthesis and reactivity of 6‐methyl‐4H‐furo[3,2c]pyran‐3,4‐dione

An efficient synthesis of 3‐bromoacetyl‐4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one by bromination of dehydroacetic acid in glacial acetic acid is described. Novel 4‐hydroxy‐6‐methyl‐3‐(2‐substituted‐thiazol‐4‐yl)‐2H‐pyran‐2‐ones have been prepared from the reaction of 3‐bromoacetyl‐4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one with thioamides, thiourea, and diphenylthiocarbazone. The condensation reaction of 6‐methyl‐4H‐furo[3,2c]pyran‐3,4‐dione, obtained from the reaction of 3‐bromoacetyl‐4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one with aliphatic amines, with benzaldehydes and acetophenones led to novel 2‐arylidene‐6‐methyl‐2H‐furo[3,2‐c]pyran‐3,4‐diones and 6‐(2‐arylprop‐1‐enyl)‐2H‐furo[3,2‐c]pyran‐3,4‐diones. The structure of all compounds was established by elemental analysis, IR, NMR, and mass spectra. J. Heterocyclic Chem., 2011.     

8‐Fluoro‐4‐hydroxy‐1H‐[1,2,4]triazino[4,5‐a]quinoline‐1,6(2H)‐dione: Synthesis and reactivity

A simple and versatile methodology to synthesise 4‐hydroxy‐1H‐[1,2,4]triazino[4,5‐a]quinoline‐1,6(2H)‐dione from methyl 6‐fluoro‐4‐oxo‐1,4‐dihydro‐2‐quinolinecarboxylate has been developed. It involves car‐bohydrazide formation followed by a condensation with triphosgene to form the fused [1,2,4]triazino ring. In addition, the reactivity of the [1,2,4]triazino ring has been studied.     

Synthesiss of novel 3‐(2‐thienyl)‐1,2‐diazepino[3,4‐b]quinoxalines with algicidal activity

The reaction of the quinoxaline N‐oxide 1 with thiophene‐2‐carbaldehyde gave 6‐chloro‐2‐[1‐methyl‐2‐(2‐thienylmethylene)hydrazino]quinoxaline 4‐oxide 5 , whose reaction with 2‐chloroacrylonitrile afforded 8‐chloro‐2,3‐dihydro‐4‐hydroxy‐1‐methyl‐3‐(2‐thienyl)‐1H‐1,2‐diazepino[3,4‐b]quinoxaline‐5‐carbonitrile 6 . The reaction of compound 6 with various alcohols in the presence of a base effected alcoholysis to provide the 5‐alkoxy‐8‐chloro‐2,3,4,6‐tetrahydro‐1‐methyl‐4‐oxo‐3‐(2‐thienyl)‐1H‐1,2‐diazepino[3,4‐b]‐quinoxalines 7a‐d . The reaction of compounds 7a and 7b with diethyl azodicarboxylate effected dehydrogenation to give the 5‐alkoxy‐8‐chloro‐4,6‐dihydro‐1‐methyl‐4‐oxo‐3‐(2‐thienyl)‐1H‐1,2‐diazepino[3,4‐b]‐quinoxalines 8a and 8b , respectively. Compounds 8a and 8b were found to show good algicidal activities against Selenastrum capricornutum and Nitzchia closterium.     

1‐[4‐(Methyl­sulfonyl)­phenyl]‐5‐phenyl‐1H‐pyrazole derivatives

Three related compounds containing a pyrazole moiety with vicinal phenyl rings featuring a methyl­sulfonyl substituent are described, namely 3‐methyl‐1‐[4‐(methyl­sulfonyl)­phenyl]‐5‐phenyl‐1H‐pyrazole, C₁₇H₁₆N₂O₂S, ethyl 1‐[4‐(methyl­sul­fonyl)­phenyl]‐5‐phenyl‐1H‐pyrazole‐3‐carboxyl­ate, C₁₉H₁₈N₂O₄S, and 1‐[4‐(methyl­sulfonyl)­phenyl]‐3‐[3‐(morpholino)­phenoxy­methyl]‐5‐phenyl‐1H‐pyrazole, C₂₇H₂₇N₃O₄S. The design of these compounds was based on celecoxib, a selective cyclo­oxy­genase‐2 (COX‐2) inhibitor, in order to study the influence of various substituents on COX‐2 and 5‐lipoxy­genase (5‐LOX) inhibition.     

Green One‐Pot Solvent‐Free Synthesis of Pyrazolo[1,5‐a]pyrimidines,Azolo[3,4‐d]pyridiazines,and Thieno[2,3‐b]pyridines Containing Triazole Moiety

Synthesis of pyrazolo[1,5‐a]pyrimidines, [1,2,4]triazolo[1,5‐a]pyrimidine, 8,10‐dimethyl‐2‐(5‐methyl‐1‐phenyl‐4,5‐dihydro‐1H‐1,2,3‐triazol‐4‐yl)pyrido[2′,3′:3,4]‐pyrazolo[1,5‐a]pyrimidine, benzo[4,5]imidazo[1,2‐a]pyrimidine via heterocyclic amines, and sodium 3‐hydroxy‐1‐(5‐methyl‐1‐phenyl‐1H‐1,2,3‐triazole‐4‐yl)prop‐2‐en‐1‐one were carried out. Also, synthesis of isoxazoles, and pyrazoles from sodium 3‐hydroxy‐1‐(5‐methyl‐1‐phenyl‐1H‐1,2,3‐triazole‐4‐yl)prop‐2‐en‐1‐one and hydroxymoyl chlorides and hydrazonoyl halides, respectively, were made. Analogously, (1,2,3‐triazol‐4‐yl)thieno[2,3‐b]pyridine derivatives were obtained from sodium 3‐hydroxy‐1‐(5‐methyl‐1‐phenyl‐1H‐1,2,3‐ triazole‐4‐yl)prop‐2‐en‐1‐one and cyanothioacetamide followed by its reacting with active methylene compounds. In addition to full characterization of all synthesized compounds, they were tested to evaluate their antimicrobial activities, and some compounds showed competitive activities to those of tetracycline, the typical antibacterial drug, and clotrimazole, the typical antifungal drug.     

Synthesis of Some 7H‐s‐Triazolo[3,4‐b]‐1,3,4‐thiadiazine Derivatives

The cyclization of 1‐amino‐2‐mercapto‐5‐[5‐methyl‐1‐(4‐methylphenyl)‐1,2,3‐triazol‐4‐yl]‐1,3,4‐triazole with various α‐haloketone in absolute ethanol yields 7H‐3‐[5‐methyl‐1‐(4‐methylphenyl)‐1,2,3‐triazol‐4‐yl]‐6‐substituted‐s‐triazolo[3,4‐b]‐1,3,4‐thiadiazines and their structures are established by elemental analysis, MS, IR and ¹H NMR spectral data.     

Novel regioselective synthesis of 3′H,4H‐spiro[chromene‐3,2′‐[1,3,4]thiadiazol]‐4‐one containing compounds

A variety of 3″,5″‐diaryl‐3″H,4′H‐dispiro[cyclohexane‐1,2′‐chromene‐3′,2″‐[1,3,4]thiadiazol]‐4′‐ones 3a‐c were synthesized regioselectively through the reaction of 4′H,5H‐trispiro[cyclohexane‐1,2′‐chromene‐3′,2″‐[1,3,4]oxadithiino[5,6‐c]chromene‐5″,1″′‐cyclohexan]‐4′‐one ( 1 ) with nitrilimines (generated in situ via triethylamine dehydrohalogenation of the corresponding hydrazonoyl chlorides 2a‐c ) in refluxing dry toluene. Single crystal X‐ray diffraction studies of 3a,b add support for the established structure. Similarly, 3′,5′‐diaryl‐2,2‐dimethyl‐3′H,4H‐spiro[chromene‐3,2′‐[1,3,4]thiadiazol]‐4‐ones 5a‐c were obtained in a regioselective manner through the reaction of 2,2,5′,5′‐tetramethyl‐4H,5′H‐spiro[chromene‐3,2′‐[1,3,4]oxadithiino[5,6‐c]chromen]‐4‐one ( 4a ) with nitrilimines under similar reaction conditions. On the other hand, reaction of 2,5′‐diethyl‐2,5′‐dimethyl‐4H,5′H‐spiro[chromene‐3,2′‐[1,3,4]oxadithiino‐[5,6‐c]chromen]‐4‐one ( 4b ) with nitrilimines in refluxing dry toluene afforded the corresponding 3′,5′‐diaryl‐2‐ethyl‐2‐methyl‐3′H,4H‐spiro[chromene‐3,2′‐[1,3,4]thiadiazol]‐4‐ones 5d‐f as two unisolable diastereoisomeric forms.     

Transformation of 4‐oxo‐4H‐[1]‐benzopyran‐3‐carboxaldehydes into pyrazolo[3,4‐B]pyridines

Reaction of 6‐methyl‐4‐oxo‐4H‐[1]‐benzopyran‐3‐carboxaldehyde 1 with 5‐amino‐3‐methyl‐1‐phenylpyrazole 2 in alcoholic reaction media in the presence of 4‐toluenesulfonic acid as catalyst afforded 5‐(2‐hydroxy‐5‐methylbenzoyl)‐3‐methyl‐1‐phenyl‐1H‐pyrazolo[3,4‐b]pyridine 3 and 2‐methoxy‐6‐methyl‐3‐(3‐methyl‐1‐phenylpyrazol‐5‐ylaminomethylene)chroman‐4‐one 7 . We explain the mechanism of formation of both products on the basis of kinetic study of individual reaction steps.     

Preparation of 2,3‐dihydro‐1H,5H‐pyrido[3,2,1‐ij]quinoline‐1,5‐dione derivatives

The 2,3‐dihydro‐7‐methyl‐1H,5H‐pyrido[3,2,1‐ij]quinoline‐1,5‐dione derivatives 9 and 10 were prepared from 3‐(5,7‐dimethoxy‐4‐methyl‐2‐oxo‐2H‐quinolin‐1‐yl)propionitrile ( 6 ). Cyclodehydration of the amide 8 gave 1,2‐dihydro‐7,9‐dimethoxy‐6‐methylpyimido[1,2‐a]quinolin‐3‐one ( 11 ).     

Synthesis and reactions of 3‐amino‐2‐methyl‐3H‐[1,2,4]triazolo[5,1‐b]‐quinazolin‐9‐one and 2‐hydrazino‐3‐phenylamino‐3H‐quinazolin‐4‐one

The reaction of 3‐N‐(2‐mercapto‐4‐oxo‐4H‐quinazolin‐3‐yl)acetamide ( 1 ) with hydrazine hydrate yielded 3‐amino‐2‐methyl‐3H‐[1,2,4]triazolo[5,1‐b]quinazolin‐9‐one ( 2 ). The reaction of 2 with o‐chlorobenzaldehyde and 2‐hydroxy‐naphthaldehyde gave the corresponding 3‐arylidene amino derivatives 3 and 4 , respectively. Condensation of 2 with 1‐nitroso‐2‐naphthol afforded the corresponding 3‐(2‐hydroxy‐naphthalen‐1‐yl‐diazenyl)‐2‐methyl‐3H‐[1,2,4]triazolo[5,1‐b]quinazolin‐9‐one ( 5 ), which on subsequent reduction by SnCl₂ and HCl gave the hydrazino derivative 6. Reaction of 2 with phenyl isothiocyanate in refluxing ethanol yielded thiourea derivative 7. Ring closure of 7 subsequently cyclized on refluxing with phencyl bromide, oxalyl dichloride and chloroacetic acid afforded the corresponding thiazolidine derivatives 8, 9 and 10 , respectively. Reaction of 2‐mercapto‐3‐phenylamino‐3H‐quinazolin‐4‐one ( 11 ) with hydrazine hydrate afforded 2‐hydrazino‐3‐phenylamino‐3H‐quinazolin‐4‐one ( 12 ). The reactivity 12 towards carbon disulphide, acetyl acetone and ethyl acetoacetate gave 13, 14 and 15 , respectively. Condensation of 12 with isatin afforded 2‐[N‐(2‐oxo‐1,2‐dihydroindol‐3‐ylidene)hydrazino]‐3‐phenylamino‐3H‐quinazolin‐4‐one ( 16 ). 2‐(4‐Oxo‐3‐phenylamino‐3,4‐dihydroquinazolin‐2‐ylamino)isoindole‐1,3‐dione ( 17 ) was synthesized by the reaction of 12 with phthalic anhydride. All isolated products were confirmed by their ir, ¹H nmr, ¹³C nmr and mass spectra.     

Reaction of 2‐acyl‐6‐methylbenzo[b]furan‐3‐acetic acids derivatives with hydrazine

Reaction of 2‐acyl‐6‐methylbenzo[b]furan‐3‐acetic acids and their derivatives such as amides and esters with hydrazine does not give expected 1‐alkyl‐5H‐benzofuro[2,3‐e]diazepin‐4‐ones ones but results in 2‐amino‐7‐methyl‐2H‐benzo[4,5]furo[2,3‐c]pyridin‐3‐ones or (3‐R‐6‐methylbenzo[b]furan‐2‐yl)alkyl ketone azines.