Simple procedure for preparation of quinoxalin-2(1H)-one 3-[Oxo(cyclo)alkyl(idene)] derivatives

A simple preparative procedure was developed for 3-(2-oxoalkylidene)-3,4-dihydroquinoxalin-2(1H)-ones, 4,5-dihydroxy-1-[3-oxo-3,4-dihydroquinoxalin-2(1H)-ylidene]-3,5-octadiene-2,7-dione, and 3-(2,3-dihydroxy-4-methyl-5-oxo-1,3-cyclopentadien-1-yl)quinoxalin-2(1H)-one by reaction of methyl ketones first with diethyl oxalate in the presence of sodium, and then with o-phenylenediamine.     

Five-membered 2,3-dioxoheterocycles: LXXIII. Synthesis and thermolysis of 3-acylpyrrolo[1,2-a]quinoxaline-1,2,4(5H)-triones

Reactions of (Z)-3-(phenacylidene-2-oxo)-3,4-dihydroquinoxalin-2(1H)-ones and (Z)-3-(3,3-dimethyl-2-oxobutylidene)-3,4-dihydroquinoxalin-2(1H)-one with oxalyl chloride led to the formation of 3-acyl-1Hpyrrolo[1,2-a]quinoxaline-1,2,4(5H)-triones that at the thermal decarbonylation generated acyl(3-oxoquinoxalin-2-yl)ketenes which underwent the intramolecular stabilization giving 3-acylfuro[3,2-b]quinoxalin-2(4H)-ones.     

Five-membered 2,3-dioxo heterocycles: LVII. Recyclization of 3-pivaloylpyrrolo[1,2-a]quinoxaline-1,2,4(5H)-triones by the action of o-phenylenediamine. Crystalline and molecular structure of 3-[3,3-dimethyl-2-oxo-1-(3-oxo-3,4-dihydroquinoxalin-2-yl)butyl]-1-phenylquinoxalin-2(1H)-one

3-[(Z)-3,3-Dimethyl-2-oxobutylidene]-3,4-dihydroquinoxalin-2(1H)-one and its 1-phenyl-substituted analog reacted with oxalyl chloride to give the corresponding 3-pivaloylpyrrolo[1,2-a]quinoxaline-1,2,4(5H)-triones. Reactions of the latter with o-phenylenediamine led to the formation of 3,3′-(3,3-dimethyl-2-oxobutane-1,1-diyl)di[quinoxalin-2(1H)-ones]. Original Russian Text ? K.S. Bozdyreva, Z.G. Aliev, A.N. Maslivets. 2008, published in Zhurnal Organicheskoi Khimii, 2008, Vol. 44, No. 4, pp. 612–616. For communication LVI, see [1].     

Maleic acid derivatives in the synthesis of 3-substituted 3,4-dihydroquinoxalin-2(1H)-ones

A process for preparing 3-substituted 3,4-dihydroquinoxalin-2(1H)-ones is proposed. It is based on the reaction of o-phenylenediamine with amides, di- and mono-esters of maleic acid as well as (E)-3-(5-phenyl-1,3,4-oxadiazol-2-yl)acrylic acid in the presence of N,N′-carbonyl-diimidazole.     

3-Methylidene-2,4-dioxo-4-pentafluorophenylbutanoates in the Synthesis of Heterocycles

3-Ethoxy- and 3-arylaminomethylidene-2,4-dioxo-4-pentafluorophenylbutanoates undergo cyclization by the action of hydrazine hydrate and phenylhydrazine to give ethyl 4-pentafluorobenzoylpyrazole-5-carboxylates. The reaction of 3-ethoxymethylidene-2,4-dioxo-4-pentafluorophenylbutanoate with o-phenylene-diamine leads to formation of 3-[2-(2-aminophenylamino)-1-pentafluorobenzoylethenyl]-1,2-dihydroquinoxa-lin-2-one. 3-Arylaminomethylidene-2,4-dioxo-4-pentafluorophenylbutanoates react with o-phenylenediamine to afford 3-(1-aryl-5,6,7,8-tetrafluoro-4-oxo-1,4-dihydroquinolin-3-yl)-1,2-dihydroquinoxalin-2-ones and/or 3-(2-arylamino-1-pentafluorobenzoylethenyl)-1,2-dihydroquinoxalin-2-ones.     

Condensation of Ethyl 2-Oxoindoline-3-glyoxylate with o-Aminophenol and o-Phenylenediamine

A method is presented for the synthesis of 3-(2-oxo-1,2-dihydro-3H-indol-3-ylidene)-1,4-dihydroquinoxalin-2-one and 2-(2-oxo-1,2-dihydro-3H-indol-3-ylidene)-2H-1,4-benzoxazin-3(4H)-one by the reaction of ethyl 2-oxoindoline-2-glyoxylate with o-aminophenol and o-phenylenediamine. Proposed reaction mechanisms are presented.     

Three-component couplings for the synthesis of pyrroloquinoxalinones by azomethine ylide 1,3-dipolar cycloaddition chemistry

1-Methyl-3,4-dihydroquinoxalin-2(1H)-one was heated with a range of aldehydes to generate intermediate azomethine ylides which underwent [3 + 2] cycloaddition reactions with N-methyl or N-phenylmaleimide to give substituted tetrahydropyrroloquinoxalinones. Only one (racemic) stereoisomer was formed in each case and the stereochemical outcome was verified by single crystal X-ray analysis. The products from this multicomponent reaction could be oxidised with DDQ to the pyrroloquinoxalinones.     

Five-membered 2,3-dioxo heterocycles: XCVII. Reaction of 3-aroylpyrrolo[1,2-a]quinoxaline-1,2,4(5H)-triones with Fischer’s base

3-Aroylpyrrolo[1,2-a]quinoxaline-1,2,4(5H)-triones reacted with 1,3,3-trimethyl-2-methylidene-2,3-dihydro-1H-indole (Fischer’s base) to give (2Z)-1-aryl-2-[3-oxo-3,4-dihydroquinoxalin-2(1H)-ylidene]-5-(1,3,3-trimethyl-2,3-dihydro-1H-indol-2-ylidene)pentane-1,3,4-triones.     

Rearrangement in the series of 3-(2-aryl-2-oxoethyl)-3,4-dihydroquinoxalin-2(1H)-ones

4-Acetyl- and 4-succinyl-3-(2-aryl-2-oxoethyl)-3,4-dihydroquinoxalin-2(1H)-ones undergo the rearrangement into (Z)-2-(3-arylquinoxalin-2-ylidene)acetic acids accompanied by the elimination of the acyl groups. The nitration of 3-(2-oxo-2-phenylethyl)-3,4-dihydro-quinoxalin-2(1H)-one affords 5-nitro- and 7-nitro-2-carboxymethylidenequinoxalines. The bromination of quinoxalin-2-ones in AcOH gives 3-aryl-2-carboxymethylidenequinoxalines and the corresponding 7-bromo derivatives, with the former products predominating.     

Rapid alkenylation of quinoxalin-2(1H)-ones enabled by the sequential Mannich-type reaction and solar photocatalysis

Herein, a rapid alkenylation of quinoxalin-2(1H)-ones enabled by a combination of Mannich-type reaction and solar photocatalysis is demonstrated. A wide range of functional groups are compatible, affording the corresponding products in moderate-to-good yields. Control experiments illustrate that the in situ generated ¹O₂ plays a central role in this reaction. This green and efficient strategy provides a practical solution for the synthesis of potentially bioactive compounds that containing a 3,4-dihydroquinoxalin-2(1H)-one structure.     

Five-membered 2,3-dioxo heterocycles: LXXIV. Recyclization of 3-aroylpyrrolo[1,2-a]quinoxaline-1,2,4(5H)-triones by the action of benzohydrazides. Crystalline and molecular structure of N-[2,4-dihydroxy-5-oxo-3-(3-oxo-3,4-dihydroquinoxalin-2-yl)-2-phenyl-2,5-dihydro-1H-pyrrol-1-yl]benzamide

Recyclization of 3-aroyl-1H-pyrrolo[1,2-a]quinoxaline-1,2,4(5H)-triones by the action of benzoic acid hydrazides gave N-[2,4-dihydroxy-5-oxo-3-(3-oxo-3,4-dihydroquinoxalin-2-yl)-2-aryl-2,5-dihydro-1H-pyrrol-1-yl]benzamides whose structure was proved by X-ray analysis.     

Fused Nitrogen-Containing Heterocycles: IV. 3-Benzoyl-2-oxo-1,2-dihydroquinoxaline Hydrazones and Flavazoles Derived Therefrom

3-Benzoyl-1,2-dihydroquinoxalin-2-one reacts with hydrazine and thiosemicarbazide to give the corresponding hydrazone and thiosemicarbazone. The reaction with arylhydrazines yields 3-(-arylazobenzylidene)-1,2,3,4-tetrahydroquinoxalin-2-ones which are tautomeric to the respective arylhydrazones. On heating in boiling acetic acid, the products of both types undergo intramolecular cyclocondensation with formation of 3-phenylpyrazolo[3,4-b]quinoxalines (3-phenylflavazoles). 3-Benzoyl-1,2-dihydroquinoxalin-2-one thiosemicarbazone gives rise to flavazole structure only in the presence of methyl 3-chloro-2-oxo-3-phenylpropionate as a trap of thiocarbamoyl moiety. The cyclization of 3-(-hydrazonobenzyl)-1,2-dihydroquinoxalin-2-one is accompanied by formation of quinoxalyl ketone azine.     

A convenient synthesis of (z)-3-(α-alkoxycarbonyl-α-cyanomethylene)-2-oxo-1,2,3,4-tetrahydroquinoxalines and related compounds

(Z)-3-(α-Alkoxycarbonyl-α-cyanomethylene)-2-oxo-1,2,3,4-tetrahydroquinoxalines 3 and (Z)-3-(α-alkoxycarbonyl-α-cyanomethylene)-3,4-dihydrobenzo[g]quinoxalin-2(1H)-ones 5 possessing various alkoxycarbonyl groups were prepared in good yields directly from the reaction of dialkyl (E)-2,3-dicyanobutendioates 1 with o-phenylenediamine ( 2 ) or with 2,3-diaminonaphthalene ( 4 ), respectively. Furthermore, 2,3-diaminopyridine ( 6 ) and 3,4-diaminopyridine ( 7 ) were reacted with the diethyl ester 1b to give (Z)-2-(α-cyano-α-ethoxycarbonylmethylene)-1,2-dihydro-4H-pyrido[2,3-b]pyrazin-3-one ( 8 ) and (Z)-3-(α-cyano-α-ethoxycarbonylmethylene)-3,4-dihydro-1H-pyrido[3,4-b]pyrazin-2-one ( 9 ), respectively. The structural studies of 3, 5, 8 , and 9 were carried out by nmr experiments in some details.     

Reaction of 2-(2-oxo-2,3-dihydro-1<Emphasis Type="Italic">H</Emphasis>-indol-3-ylidene)acetic acid esters with benzene-1,2-diamine and 2-aminobenzenethiol

2-(2-Oxo-2,3-dihydro-1H-indol-3-ylidene)acetic acid esters reacted with benzene-1,2-diamine or 2-aminobenzenethiol to give (2-oxo-2,3-dihydro-1H-indol-3-yl)-substituted 3,4-dihydroquinoxalin-2(1H)-ones or 2H-1,4-benzothiazin-3(4H)-ones.     

Studies in spiroheterocycles,Part XV. Investigation of the reaction of 3-(2-oxocycloalkylidene)-indol-2-ones with thiourea and urea derivatives

The reaction of 3-(2-oxocycloalkylidene)indol-2-one 1 with thiourea and urea derivatives has been investigated. Reaction of 1 with thiourea and urea in ethanolic potassium hydroxide media leads to the formation of spiro-2-indolinones 2a-f in 40–50% yield and a novel tetracyclic ring system 4,5-cycloalkyl-1,3-diazepino-[4,5-b]indole-2-thione/one 3a-f in 30–35% yield. 3-(2-Oxocyclopentylidene)indol-2-one afforded 5′,6′-cyclopenta-2′-thioxo/ oxospiro[3H-indole-3,4′(3′H)pyrimidin]-2(1H)-ones 2a,b and 3-(2-oxocyclohexylidene)indol-2-one gave 2′,4′a,5′,6′,7′,8′- hexahydro-2′-thioxo/oxospiro[3H-indole-3,4′ (3′H)-quinazolin]-2(1H)-ones 2c-f . Under exactly similar conditions, reaction of 1 with fluorinated phenylthiourea/cyclohexylthiourea/phenylurea gave exclusively spiro products 2g-1 in 60–75% yield. The products have been characterized by elemental analyses, ir pmr. ¹⁹F nmr and mass spectral studies.     

Quinazolines and 1,4-benzodiazepines. XLVI. Photochemistry of nitrones and oxaziridines

The cyclic nitrones 7-chloro-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepin-2-one 4-oxide ( 5a ) and 1,3-dihydro-7-methylthio-5-phenyl-2H-1,4-benzodiazepin-2-one 4-oxide ( 5b ) are photoisomerized to readily isolable oxaziridines, 7-chloro-4,5-epoxy-5-phenyl-1,3,4–5-tetrahydro-2H-1,4-benzodiazepin-2-one ( 6a ) and 4,5-epoxy-5-phenyl-1,3,4,5-tetrahydro-7-methylthio-2H-1,4-benzo-diazepin-2-one ( 6b ). Oxaziridine 6b upon further irradiation gave ring expansion and ring contraction products, 4,6-dihydro-2-phenyl-9-methylthio-5H-1,3,6-benzoxadiazocin-5-one ( 7b ) and 4-benzoyl-3,4-dihydro-6-methylthioquinoxalin-2(1H)-one ( 8b ) respectively. The ring contraction product, 4-benzoyl-6-chloro-3,4-dihydroquinoxalin-2(1H)-one ( 8a ), was obtained from irradiation of oxaziridine 6a .     

Five-Membered 2,3-Dioxo Heterocycles: L. Synthesis and Thermolysis of 3-Aroyl- and 3-Hetaroyl-5-phenyl-1,2,4,5-tetrahydropyrrolo[1,2-<Emphasis Type="Italic">a</Emphasis>]quinoxalin-1,2,4-triones

(Z)-3-Phenacylidene- and (Z)-3-hetaroylmethylidene-1-phenyl-1,2,3,4-tetrahydroquinoxalin-2-ones react with oxalyl chloride to give 3-acyl-5-phenyl-1,2,4,5-tetrahydropyrrolo[1,2-a]quinoxaline-1,2,4-triones. Thermolysis of the latter generates acyl(3-oxo-4-phenyl-3,4-dihydroquinoxalin-2-yl)ketenes which are stabilized via [4 + 2]-cyclodimerization followed by [1,3]-acylotropic shift to afford 4-acyl-3-acyloxy-2-(3-oxo-4-phenyl-3,4-dihydroquinoxalin-2-yl)-6-phenyl-5,6-dihydro-1H-pyrido[1,2-a]quinoxaline-1,5-diones.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 7, 2005, pp. 1101–1108.Original Russian Text Copyright © 2005 by Bozdyreva, Smirnova, Maslivets.     

Reinvestigation of the condensation of 2-hydrazinobenzothiazole with ethyl acetoacetate

The reaction of 2-hydrazinobenzothiazole (1) with ethyl acetoacetate has twice been reported to yield a fused triazepinobenzothiazolone, namely, 3-methyl[1,2,4]triazepino[3,4-b]benzothiazol-5(4H)-one (4). We have repeated this work and reassigned the reaction product as 2-(2-benzothiazolyl)-1,2-dihydro-5-methyl-3H-pyrazol-3-one (5) on the basis of X-ray crystallography.     

N,N′-Linked 1,2-benzisothiazol-3(2H)-one 1,1-dioxides: synthesis, biological activity, and derived radicals

A number of N,N′-linked benzoannelated isothiazol-3(2H)-one 1,1-dioxides, not available via oxidation of isothiazolium salts, were obtained with good yields by reaction of N-amino heterocycles with 2-chlorosulfonylbenzoyl chloride and evaluated for their inhibitory activity toward human leukocyte elastase (HLE) and acetylcholinesterase (AChE). 2-(Phthalimid-1-yl)-1,2-benzisothiazol-3(2H)-one 1,1-dioxide and 2-(2-methyl-4-oxo-3(4H)-quinazolinyl)-1,2-benzisothiazol-3(2H)-one 1,1-dioxide were found to be inhibitors of HLE and tested as potential precursors of nitrogen-centered radicals using 266 nm laser flash photolysis.     

Gold-catalyzed consecutive [1,2] alkyl migration-oxygen transfer reaction of 2-alkynyl-1-tetralones

Gold-catalyzed isomerization of 2-alkynyl-1-tetralones afforded the corresponding 2-naphthylmethyl ketones in good to high yields. For example, the reaction of 2-{4-(methoxyphenyl)methyl}-2-(phenylethynyl)-3,4-dihydronaphthalen-1(2H)-one and 2-benzyl-2-(phenylethynyl)-3,4-dihydronaphthalen-1(2H)-one in the presence of 5 mol % of (Ph₃P)AuCl and 5 mol % of AgOTf in THF at 50 °C gave 2-{1-(4-methoxyphenylmethyl)naphthalen-2-yl}-1-(4-methoxyphenyl)ethanone and 2-(1-benzylnaphthalen-2-yl)-1-phenylethanone in 85% and 96% yields, respectively. The present reaction proceeds through [1,2] alkyl migration followed by oxygen transfer.