Syntheses of 4-(benzo[b]furan-2 or 3-yl)- and 4-(benzo[b]-thiophen-3-yl)piperidines with 5-HT2 antagonist activity

The syntheses of 4-(benzo[b]furan-3-yl)piperidines, 4-(benzo[b]furan-2-yl)piperidines and 4-(benzo[b]thiophen-3-yl)piperidines with 5-HT₂ antagonist activity are described. Reaction of 1-acetyl-4-(2,4-difluorobenzo-yl)piperidine 2 with methyl glycolate gave methyl 6-fluoro-3-(1-acetylpiperidin-4-yl)benzo[b]furan-2-carboxylate 3 , which was converted to 2-[2-[4-(benzo[b]furan-3-yi)piperidin-1-yl]ethyl-5,6,7,8-tetrahydro-1,2,4-triazolo-[4,3-a]pyridin-3(2H)-one hydrochloride 9 . Analogous benzo[b]furans 17a-d and benzo[b]thiophenes 10a,b and 18a were prepared by a similar method. Cyclization of 4-fluoro-2-(4-pyridinylmethoxy)acetophenones 20a,b afforded 4-(benzo[b]furan-2-yl)pyridines 21a,b , which were converted to 2-[2-[4-(benzo[b]furan-2-yl)-piperidin-1-yl]ethyl-5,6,7,8-tetrahydro-1,2,4-triazolo[4,3-a]pyridin-3(2H)-one hydrochlorides 24a,b. Among them, benzo[b]furans 9 and 17a,d and benzo[b]thiophenes 10 and 18a showed potent 5-HT₂ antagonist activity in vitro.     

A new type of deoxygenation of quinoxaline N-oxides

The reaction of 6-chloro-2-[2-(p-chlorobenzylidene)-1-methylhydrazino]quinoxaline 4-oxide 3a or 2-[2-(p-bromobenzylidene)-1-methylhydrazino]-6-chloroquinoxaline 4-oxide 3b with dimethyl acetylenedicarboxylate under reflux in N,N-dimethylformamide resulted in deoxygenation to give 6-chloro-2-[2-(p-chlorobenzylidene)-1-methylhydrazino]quinoxaline 4a or 2-[2-(p-bromobenzilidene)-1-methylhydrazino]-6-chloroquinoxaline 4b , respectively, while the reaction of compound 3a or 3b with dimethyl acetylenedicarboxylate under reflux in dioxane precipitated dimethyl 8-chloro-4-[2-(p-chlorobenzyli-dene)-1-methylhydrazino]-3aH-isoxazolo[2,3-a]quinoxaline-2,3-dicarboxylate 6a or dimethyl 4-[2-(p-bromobenzylidene)-1-methylhydrazino]-8-chloro-3aH-isoxazolo[2,3-a]quinoxaline-2,3-dicarboxylate 6b , respectively. Further refluxing of compound 6a or 6b in N,N-dimethylformamide provided compound 4a or 4b , respectively.     

Synthesis of 1-[3-methyl-2(3H)-benzazolon-5- or 6-yl]-4-{4-[cis-2-(2,4-dichlorophenyl)-2-(1H-imidazol-1-yl-methyl)-1,3-dioxolan-4-yl]methyleneoxyphenyl}piperazines

Reactions of 3-methyl-6-[4-(4-hydroxyphenyl)-1-piperazinyl]-2(3H)-benzoxazolone, 3-methyl-6-[4-(4-hydroxy-phenyl)-1-piperazinyl]-2(3H)-benzothiazolone and 1,3-dimethyl-5-[4-(4-hydroxyphenyl)-1-piperazinyl]-2(3H)-benzimidazolone with cis-{[2-(2,4-dichlorophenyl) -2-(1H-imidazol-1-ylmethyl)]-1,3-dioxolan-4-yl}methyl meth-anesulfonate in the presence of sodium hydride furnish the title compounds.     

Nitrogen bridgehead compounds. Part 88. Synthesis of 3H, 7H-[1,4]diazepino[3,4-b]quinazoline-3,7-diones

3H,7H-[1,4]Diazepino[3,4-b]quinazolone-3,7-diones 9, 11 were synthesized starting from 2-(1-bromo-ethyl)quinazolin-4(3H)-ones 3 and 17 via 2-[1-(4-methoxyphenylamino)ethyl]quinazolin-4(3H)-ones 4 and 18. Cyclization of 3-[2-(1-bromoethyl)-4-oxo-3,4-dihydroquinazolin-3-yl)propionic acid 14 by the action of triethylamine provided the first representative of the tricyclic 7H-[1,4]oxazepino[3,4-b]quinazoline-3,7-dione system, compound 15. The new tricyclic derivatives 9, 11 and 15 are characterized by uv, ir and ¹H nmr spectroscopy.     

Preparation of novel heterocyclic systems from isatoic anhydrides

Isatoic anhydride ( 1a ) and 5-chloroisatoic anhydride ( 1b ) were treated with 2-(1-methylhydrazino)ethanol ( 2 ) to produce 2-aminobenzoic acid 2-(2-hydroxyethyl)-2-methylhydrazide ( 3a ) and its 5-chloro analog 3b , respectively. Treatment of 3a and 3b with carbon disulfide gave, respectively, 2,3-dihydro-3-[(2-hydroxyethyl)methylamino]-2-thioxo-4-(1H)quinazolinone ( 4a ) and its 6-chloro analog 4b . Compounds 4a and 4b afforded 5,6-dihydro-5-methyl-2-thioxo-4H,8H-[1,3,5,6]oxathiadiazocino[4,5-b]quinazolin-8-one ( 5a ) and its 10-chloro analog 5b , respectively, upon treatment with thiophosgene. Compound 5a could be produced directly from 3a and thiophosgene. Treatment of 4a and 4b with trifluoroacetic anhydride followed by potassium carbonate gave 3,4-dihydro-4-methyl-2H,6H-[1,3,4]thiadiazino[2,3-b]quinazolin-6-one ( 7a ) and its 8-chloro analog 7b , respectively. Treatment of 4a with thionyl chloride also gave 7a , but 4b and thionyl chloride afforded a mixture of 7b and 8-chloro-3,4-dihydro-4-methyl-2H,6H-[1,3,4]oxadiazino[2,3-b]quinazolin-6-one ( 10 ). The dimethyl analogs of 4a and 4b ( 13a and 13b ) upon treatment with thiophosgene afforded 3,4-dihydro-2,2,4-trimethyl-2H,6H-[1,3,4]oxadiazino[2,3-b]quinazolin-6-one ( 14a ) and its 8-chloro analog 14b , respectively.     

On the condensation of 2,2-difluoro-4-methyl-benzo[d]-1,3,2-dioxaborines with cyano acetic acid derivatives. Formation and transformation of 3-cyano-4-methyl-benzo[b]pyran-2-ones and their 2-imine precursors

Summary By condensation of 2,2-difluoro-4-methyl-benzo[d]-1,3,2-2H-dioxaborines (12) with cyano acetic acid derivatives in presence of weak bases, 3-cyano-4-methyl-benzo[b]pyran-2-ones (13) or their 3-cyano-4-methyl-benzo[b]pyran-2-imine precursors (14) are available in satisfactory yields.

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Zur Kondensation von 2,2-Difluor-4-methyl-benzo[d]-1,3,2-2H-dioxaborinen mit Cyanessigsäure- Derivaten. Bildung und Umwandlung von 3-Cyano-4-methyl-benzo[b]pyran-2-onen und ihrer 2-Imino-Vorstufen

Zusammenfassung Durch Kondensation von 2,2-Difluor-4-methyl-benzo[d]-1,3,2-2H-dioxaborinen (12) mit Cyanessigsäure-Derivaten in Gegenwart von Hilfsbasen entstehen in befriedigenden Ausbeuten 3-Cyan-4-methyl-benzo[b]pyran-2-one (13) oder ihre 3-Cyan-4-methyl-benzo[b]pyran-2-imino-Vorstufen (14).

     

New Monoterpene-Substituted Dihydrochalcones from Piper aduncum

Five New unusual monoterpene-substituted dihydrochalcones, the adunctins A–E (1″S)-1-{2′-hydroxy-4′-methoxy-6′-[4″-methyl-1″-(1?-methylethyl)cyclohex-3″ -en-1″ -yloxy]phenyl}-3-phenylpropan-1-one ( 1 ), (5aR*,8R*,9aR*)-3-phenyl-1-[5′,8′,9′,9′a-tetrahydro-3′-hydroxy-1′-methoxy-8′-(1″-methylethyl)-5′-a-methyldibenzo-[b,d]furan-4′-yl]propan-1-one ( 2 ), (2′R*,4″S*)-1-{6′-hydroxy-4′-methoxy-4″-(1?-methylethyl)spiro[benzo[b]-furan-2′(3′H),1″ -cyclohex-2″ -en]-7′-yl}-3-phenylpropan-1-one ( 3 ), (2′R*,4″R*)-1-{6′-hydroxy-4′-methylethyl-4″-(1?-methylethyl)spiro[benzo[b]furan-2′(3′H),1″-cyclohex-2″-en]-7′-yl}-3-phenypropan-1-one ( 4 ), and (5′aR*,6′S*, 9′R*,9′aS*)-1-[5′a,6′,7′,8′,9′a-hexahydro-3′,6′-methoxy-6′-methyl-9′-(1″-methylethyl)dibenzo[b,d]-furan-4′-yl]-3-phenylpropan-1-one ( 5 ) were isolated from the leaves of Piper aduncum (Piperaceae) by preparative liquid chromatography. In addition, (?)-methyllindaretin ( 6 ), trans-phytol, and α-tocopherol ( = vitamin E) were also isolated and identified. The structures were elucidated by spectroscopic methods, including 1D- and 2D-NMR spectroscopy as well as single-crystal X-ray diffraction analysis. The antibacterial and cytotoxic potentials of the isolates were also investigated.     

Synthesis of 2-[3-(trifluoromethyl)phenyl]furo[3,2-<Emphasis Type="Italic">c</Emphasis>]pyridine derivatives

2-[3-(Trifluoromethyl)phenyl]-4,5-dihydrofuro[3,2-c]pyridin-4-one (I) was prepared by a three-step synthesis. Its reaction with phosphorus sulfide rendered thione II which was methylated to 2-[3-(Trifluoromethyl)phenyl]-4-methylsulfanylfuro[3,2-c]pyridine (III). 5-Methyl-2-[3-(trifluoromethyl)phenyl]-4,5-dihydrofuro[3,2-c]pyridin-4-one (IV) was obtained by the reaction of I with methyl iodide in PTC conditions. The chlorine atom in derivate V was replaced with heterocyclic secondary amines via nucleophilic substitution and 4-substituted furopyridines VIa and VIb were thus prepared. 2-[3-(Trifluoromethyl)phenyl]furo[3,2-c]pyridine-4-carboxylic acid (VII) was obtained by hydrolysis of the corresponding carbonitrile Va.     

Synthesis of 1-methyl-7-(trifluoromethyl)-1H-pyrido[2,3-c][1,2]thiazin-4(3H)-one 2,2-dioxide

The reaction of methyl 2-bromo-6-(trifluoromethyl)-3-pyridinecarboxylate ( 1 ) with methanesulfonamide gave methyl 2-[(methylsulfonyl)amino]-6-(trifluoromethyl)-3-pyridine-carboxylate ( 2 ). Alkylation of compound 2 with methyl iodide followed by cyclization of the resulting methyl 2-[methyl(methylsulfonyl)amino]-6-(trifluoromethyl)-3-pyridinecarboxylate ( 3 ) yielded 1-methyl-7-(trifluoromethyl)-1H-pyrido[2,3-c][1,2]thiazin-4(3H)-one 2,2-dioxide ( 4 ). The reaction of compound 4 with α,2,4-trichlorotoluene, methyl bromopropionate, methyl iodide, 3-trifluoromethylphenyl isocyanate, phenyl isocyanate and 2,4-dichloro-5-(2-propynyloxy)phenyl isothiocyanate gave, respectively, 4-[(2,4-dichlorophenyl)methoxy]-1-methyl-7-(trifluoromethyl)-1H-pyrido[2,3-c][1,2]thiazine 2,2-dioxide ( 5 ), methyl 2-[[1-methyl-2,2-dioxido-7-(trifluoromethyl)-1H-pyrido[2,3-c][1,2]thiazin-4-yl]oxy]propanoate ( 6 ), 1,3,3-trimethyl-7-(trifluoromethyl)-1H-pyrido[2,3-c][1,2]thiazin-4(3H)-one 2,2-dioxide ( 7 ), 4-hydroxy-1-methyl-7-(trifluoromethyl)-N-[3-(trifluoromethyl)phenyl]-1H-pyrido[2,3-c][1,2]thiazine-3-carboxamide 2,2-dioxide ( 8 ), 4-hydroxy-1-methyl-7-(trifluoromethyl)-N-phenyl-1H-pyrido[2,3-c][1,2]thiazine-3-carboxamide 2,2-dioxide ( 9 ) and N-[2,4-dichloro-5-(2-propynyloxy)phenyl]-4-hydroxy-1-methyl-7-(trifluoromethyl)-1H-pyrido[2,3-c][1,2] thiazine-3-carboxamide 2,2-dioxide ( 10 ).     

Carbon-13 nuclear magnetic resonance study of a new ring-chain tautomerism of some pyridazine derivatives

The ¹³C NMR spectra of a number of pyridazine derivatives have been recorded in DMSO-d₆ solution and analysed. Examination of the most diagnostic resonances, with particular emphasis on those arising from the pyridazine ring system, enabled the ready establishment of the presence of a ring-chain tautomerism in 5-(o-aminophenylcarbamoyl)pyridazine-4-carboxylic acid, methyl 5-(o-aminophenylcarbamoyl)pyridazine-4-carboxylate, 5-(o-aminophenylcarbamoyl)-3,6,-dimethylpyridazine-4-carboxylic acid and 5-(2-amino-1,2-dicyanovinylenecarbamoyl)pyridazine-4-carboxylic acid. This gave rise to 3′,4′-dihydro-3′-oxospiro[pyridazine-5(2H),2′(1H)-quinoxaline]-4-carboxylic acid, methyl 3′,4′-dihydro-3′oxospiro[pyridazine-5(2H),2′(1′H)-quinoxaline]-4-carboxylate, 3′,4′-dihydro-3′-oxo-3,6-dimethylspiro[pyridazine-5(2H), 2′(1′H)-quinoxaline]-4-carboxylic acid and 5-oxo-2,3-dicyano-1,4,8,9-tetraazaspiro[5.5]undeca-2,7,10-triene-11-carboxylic acid, respectively.     

The Diels-Alder Reactivity of 2,2′-Ethylidenebis[3,5-dimethylfuran] and Exploratory Chemistry of the Mono-adducts

In the presence of Me₃Al, 1-cyanovinyl acetate added to 2,2′-ethylidenebis[3,5-dimethylfuran] ( 1 ) to give a 20:10:1:1 mixture of mono-adducts 4,5,6 , and 7 resulting from the same regiocontrol (‘para’ orienting effect of the 5-methyl substituent in 1 ). The additions of a second equiv. of dienophile to 4–7 were very slow reactions. The major mono-adducts 4 (solid) and 5 (liquid) have 2-exo-carbonitrile groups. The molecular structure of 4 (1RS,1′RS,2SR,4SR)-2-exo-cyano-4-[1-(3,5-dimethylfuran-2-yl)ethyl-7-oxabicyclo[2.2.1]hept-5-en-2-endo-yl acetate) was determined by X-ray single-crystal radiocrystallography. Mono-adducts 4 and 5 were saponified into the corresponding 7-oxanorbornenones 8 and 9 which were converted with high stereoselectivity into (1RS,1′SR,4RS,5RS,6RS)-4-[1-(3,5-dimethyl furan-2-yl)ethyl]-6-exo-methoxy-1,5-endo-dimethyl-7-oxabicyclo [2.2.1]heptan-2-one dimethyl acetal ( 12 ) and its (1′RS-stereoisomer 12a , respectively. Acetal hydrolysis of 12a followed by treatment with (t-Bu)Me₂SiOSO₂CF₃ led to silylation and pinacol rearrangement with the formation of (1RS,1′RS,5RS,6RS)-4-[(tert-butyl)dimethy lsilyloxy]-1-(3,5-dimethylfuran-2-yl)ethyl]-5-methoxy-6-methyl-3-methylidene- 2-oxabicyclo[2.2.1]heptane ( 16 ). In the presence of Me₃Al, dimethyl acetylenedicarboxylate added to 12 giving a major adduct 19 which was hydroborated and oxidized into (1RS,1′RS,2″RS,3″RS,4SR,4″RS,5 SR,6SR)-dimethyl 5-exo-hydroxy-4,6-endo-dimethyl-1-[1-(3-exo,5,5-trimeth oxy-2-endo,4-dimethyl-7-oxabicyclo[2.2.1]hept-2-yl)ethyl]-7-oxabicyclo [2.2.1]hept-2-ene-2,3-dicarboxylate ( 20 ). Acetylation of alcohol 20 followed by C?C bond cleavage afforded (1′RS,1″SR,2RS,2′″SR,3RS, 3″SR,4RS,4″SR,5RS)-dimethyl {3-acetoxy-2,3,4,5-tetrahydro-2,4-dimethyl-5-[1-(3-exo,5,5-trimethoxy ?2-endo,4-dimethyl-7-oxabicyclo[2.2.1]hept-1-yl)-ethyl]furan-2,5-diyl} bis[glyoxylate] ( 24 ).     

Investigation of the reactions of fluorine containing 3-hydrazino-5H-1, 2, 4-triazino[5, 6-b]indoles with ethyl acetoacetate. Synthesis of some novel tetracyclic ring systems

Novel tetracyclic ring systems viz. 3-methyl-1-oxo-12H-1, 2, 4-triazepino[3′,4′:3, 4][1, 2, 4]triazino[5, 6-b]indole ( 4a ) and 3-methyl-5-oxo-12H-1, 2, 4-triazepino[4′,3′:2, 3][1, 2, 4]triazino[5, 6-b]indole ( 5a ), having angular and linear structures respectively, were synthesized by the cyclization of 3-oxobutanoic acid [5H-1, 2, 4-triazino-[5, 6-b]indole-3-yl]hydrazone ( 3a ). However, cyclization of 3b (R = CH_a, R¹ = R² = H) afforded the angular product 4b exclusively. Moreover, cyclization of 3c (R = R³ = H, R¹ = F) yielded 7-fluoro-1-0xo-10H-1, 3-imidazo[2′,3′:3, 4][1, 2, 4]triazino[5, 6-b]indole ( 6c ) and 7-fluoro-3-oxo-10H-1, 3-imidazo[3′,2′:2, 3][1, 2, 4]triazino-[5, 6-b]indole ( 7c ) instead of the expected triazepinone derivatives. Compound 3d (R = R¹ = H, R² = CF₃) also gave an imidazole derivative but only one angular product was obtained. In all these reactions, formation of the angular product involving cyclization at N-4 is favoured. Characterization of these products have been done by elemental analyses, ir, pmr, ¹⁹F nmr and mass spectral studies.     

Reaction of 6-chloro-2-[1-methyl-2-(N-methylthiocarbamoyl)]-hydrazinoquinoxaline 4-oxide with dimethyl acetylenedicarboxylate

The reaction of 6-chloro-2-(1-methylhydrazino)quinoxaline 4-oxide 4a with methyl or phenyl isothiocyanate gave 6-chloro-2-[1-methyl-2-(N-methylthiocarbamoyl)hydrazino]quinoxaline 4-oxide 7a or 6-chloro-2-[1-methyl-2-(N-phenylthiocarbamoyl)hydrazino]quinoxaline 4-oxide 7b , respectively, whose reaction with dimethyl acetylenedicarboxylate afforded 6-chloro-2-[N-methyl-N-(5-methoxycarbonylmethylene-3-methyl-4-oxo-2-thioxoimidazolidin-1-yl)]aminoquinoxaline 4-oxide 8a or 6-chloro-2-[N-methyl-N-(5-methoxycarbonylmethylene-4-oxo-3-phenyl-2-thioxoimidazolidin-1-yl)]aminoquinoxaline 4-oxide 8b , respectively.     

A new method for the synthesis of novel 1-aryl-3-heteroaryl-1H-pyrazolo[3,4-b]quinoxalines

The reaction of 3-(2,3-dihydro-4-methyl-3-thioxo-4H-1,2,4-triazol-5-ylmethylene)-2-oxo-1,2,3,4-tetrahydroquinoxaline 4 with o-chlorobenzenediazonium chloride gave 3-[α-(o-chlorophenylhydrazono)-2,3-dihydro-4-methyl-3-thioxo-4H-1,2,4-triazol-5-ylmethyl]-2-oxo-1,2-dihydroquinoxaline 6 , whose refluxing in phosphoryl chloride/pyridine afforded 1-(o-chlorophenyl)-3-(2,3-dihydro-4-methyl-3-thioxo-4H-1,2,4-triazol-5-yl)-1H-pyrazolo[3,4-b]quinoxaline 7. The reactions of 6 and 7 with nitrous acid resulted in sulfur extrusion to provide 1-(o-chlorophenyl)-3-(4-methyl-4H-1,2,4-triazol-5-yl)1H-pyrazolo[3,4-b]quinoxaline 8 and 3-[α-(o-chlorophenylhydrazono)-4-methyl-4H-1,2,4-triazol-5-ylraethyl]-2-oxo-1,2-dihydroquinoxaline 9 , respectively.     

A Facile One-Step Synthesis of New Types of 8-Thiazolyl and 8-Thiadiazinyl Coumarins

N-[4-(7-Methoxy-4-methyl-2-oxo-2H-chromen-8-yl)-thiazol-2-yl]-guanidine ( 2 ) has been prepared by the condensation of 4-methyl-7-methoxy-8-(2-bromoacetyl)coumarin ( 1 ) with guanylthiourea. 4-Methyl-7-methoxy-8-[2-(N′-(1-phenyl-ethylideneisopropylidene)-hydrazino]-thiazol-4-yl]chromen-2-ones ( 3 , 4 , and 5 ) have been prepared by reaction of 4-methyl-7-methoxy-8-(2-bromoacetyl) coumarin ( 1 ) and thiosemicarbazide in presence of acetophenone or acetone without any solvent. The formation of these compounds was further confirmed by the condensation of acetophenone/acetone thiosemicarbazones with 4-methyl-7-methoxy-8-(2-bromoacetyl)coumarin ( 1 ) in anhydrous ethanol in a two-step process. Similarly 8-[2-[N′-(benzylidene)hydrazine]-thiazol-4-yl]-7-methoxy-4-methyl-chromen-2-ones ( 6 , 7 , and 8 ) have been prepared by the condensation of 4-methyl-7-methoxy-8-(2-bromoacetyl)chromen-2-one with thiosemicarbazide and various aromatic aldehydes in a single step without any solvent. The formation of these compounds was further confirmed by the condensation of appropriately substituted benzaldehyde thiosemicarbazones with 4-methyl-7-methoxy-8-(2-bromoacetyl)coumarin in anhydrous ethanol. 4-Methyl-7-methoxy-8-(2-bromoacetyl) chromen-2-one (1) upon condensation with 3,5-dimercapto-4-amino-s-triazole in anhydrous ethanol resulted in the formation of 8-(3-mercapto-3H-[1,2,4]triazolo[3,4-b]thiadiazin-6-yl)-7-methoxy-4-methyl chromen-2-one (9). This compound ( 9 ) on reaction with various alkyl and phenacyl halides in anhydrous ethanol gave corresponding 4-methyl-7-methoxy-8-[3-(2-oxo-substituted sulphanyl)-7H-[1,2,4]triazolo[3,4-b]thiadiazin-6-yl]chromen-2-ones ( 10 to 18 ). The structures of newly prepared compounds have been confirmed from analytical and spectral data.     

Synthesis of 1,2-diazepino[3,4-b]quinoxalines and pyrido[3′,4′:9,8][1,5,6]oxadiazonino[3,4-b]quinoxalines via a 1,3-dipolar cycloaddition reaction

The reaction of 6-chloro-2-(1-methylhydrazino)quinoxaline 4-oxide 8 with furfural, 3-methyl-2-thiophene-carbaldehyde, 2-pyrrolecarbaldehyde, 4-pyridinecarbaldehyde and pyridoxal hydrochloride gave 6-chloro-2-[2-(2-furylmethylene)-1-methylhydrazino]quinoxaline 4-oxide 5a , 6-chloro-2-[1-methyl-2-(3-methyl-2-thienyl-methylene)hydrazino]quinoxaline 4-oxide 5b , 6-chloro-2-[1-methyl-2-(2-pyrrolylmethylene)hydrazino]quinoxa-line 4-oxide 5c , 6-chloro-2-[1-methyl-2-(4-pyridylmethylene)hydrazino]quinoxaline 4-oxide 5d and 6-chloro-2-[2-(3-hydroxy-5-hydroxymethyl-2-methyl-4-pyridylmethylene)-1-methylhydrazino]quinoxalme 4-oxide 5e , respectively. The reaction of compound 5a or 5b with 2-chloroacrylonitrile afforded 8-chloro-3-(2-furyl)-4-hydroxy-1-methyl-2,3-dihydro-1H-1,2-diazepino[3,4-b]quinoxaline-5-carbonitrile 6a or 8-chloro-4-hydroxy-1-methyl-3-(3-methyl-2-thienyl)-2,3-dihydro-1H-1,2-diazepino[3,4-b]quinoxaline-5-carbonitrile 6b , respectively, while the reaction of compound 5e with 2-chloroacrylonitrile furnished 11-chloro-7,13-dihydro-4-hydroxy-methyl-5,14-methano-1,7-dimethyl-16-oxopyrido[3′,4′:9,8][1,5,6]oxadiazonino[3,4-b]quinoxaline 7.     

Methyl and Phenylmethyl 2-Acetyl-3-{[2-(dimethylamino)-1-(methoxycarbonyl)ethenyl]amino}prop-2-enoate in the Synthesis of heterocyclic systems: Preparation of 3-amino-4H-pyrido-[1,2-a]pyrimidin-4-ones

Methyl 2-acetyl-3-{[2-(dimethylamino)-1-(methoxycarbonyl)ethenyl]amino}prop-2-enoate ( 4 ) and phenyl-methyl 2-acetyl-3-{[2-(dimethylamino)-1(methoxycarbonyl)ethenyl]amino}prop-2-enoate ( 5 ) were prepared in three steps from the corresponding acetoacetic esters, and used as reagents for the preparation of N³-protected 3-amino-4H-pyrido[1,2-a]pyrimidin-4-ones 10 – 12 , 5H-thiazolo[3,2-a]pyrimidin-5-one 13 , 4H-pyrido[1,2-a]-pyridin-4-one 19 and 2H-1-benzopyran-2-ones 20 – 23 . Free 3-amino-4H-pyrido[1,2-a]pyrimidin-4-ones 24 – 26 were prepared from 10 – 12 by removal of the 2-(methoxycarbonyl)-3-oxobut-1-enyl or 3-oxo-2-[(phenyl-methoxy)carbonyl]but-1-envl as N-protecting group by various methods.     

The synthesis of azole derivatives from 3-[(4-methylphenyl)amino]propanehydrazide and its N′-phenylcarbamoyl derivatives, and their antibacterial activity

Abstract  

5-[2-[(4-Methylphenyl)amino]ethyl]-1,3,4-oxadiazol-2(3H)-thione, 5-[2-[(4-methylphenyl)amino]ethyl]-1,3,4-oxadiazol-2(3H)-one, N-(2,5-dimethyl-1H-pyrrol-1-yl)-3-[(4-methylphenyl)amino]propanamide, and a series of N-[(phenylcarbamoyl)amino]-3-[(4-methylphenyl)amino]propanamides and 3-[(4-methylphenyl)(phenylcarbamoyl)amino]-N-[(phenylcarbamoyl)amino]propanamides, and their thio analogues were synthesized from 3-[(4-methylphenyl)amino]propanehydrazide. 1,3,4-Oxadiazole-2(3H)-thione was converted to 4-amino-2,4-dihydro-5-[2-[(4-methylphenyl)amino]ethyl]-3H-1,2,4-triazole-3-thione, whereas cyclization of N′-phenylcarbamoyl derivatives provided thiazole, oxadiazoles, and thiadiazole, as well as triazole derivatives. Two of the synthesized compounds exhibited good antibacterial activity against Rhizobium radiobacter.     

Neue Derivate der 2-Acylamino-thiophen-(und-benzo[b]thiophen-)-3-carbonsäure sowie des ([1]Benzo-)Thieno[2,3-d]-pyrimidin-4(3H)-ons

The title substances1 and2 were prepared by acylation of the corresponding ethyl 2-amino-thiophene- (or:-4,5,6,7-tetrahydro-benzo[b]thiophene)-3-carboxylates, in some cases followed by reactions introducing a basic substituent.Additionally a group of 2-aroylamino-thiophene-(or:-4,5,6,7-tetrahydro-benzo[b]thiophene)-3-carboxamides was subjected to ring closure reactions, yielding the corresponding 2-aryl-thieno[2,3-d]pyrimidin-4(3H)-ones and 2-aryl-[1]benzothieno[2,3-d]pyrimidin-4(3H)-ones (both:3).

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Zum Teil unter Mitarbeit vonFerdinand Fuhrmann     

A study of hydrogen bonds in <Emphasis Type="Italic">p</Emphasis>-substituted calix[4]-and calix[6]arenes by <Emphasis Type="Italic">ab initio</Emphasis> and electron density functional methods

RHF/3-21G and B3LYP/3-21G methods are used to calculate the hydrogen bond energies in calix[4]-, calix[6]-, p-fluorocalix[4]-, p-fluorocalix[6]-, p-chlorocalix[4]-, p-chlorocalix[6]-, p-bromocalix[4]-, pbromocalix[6]-, p-iodocalix[4]-, p-iodocalix[6]-arenes and a number of other p-substituted calix[4]- and calix[6]arenes (R = Me, OMe, NO₂, Ac, NH₂, CN, N₂⁺). The calculations along with the structural data give evidence of the cooperative effect of hydrogen bonding. Multiple correlation (p ≥ 0.9) between the pairs of Hammett substituent constants and the calculated values of hydrogen bond energies in the corresponding p-substituted calixarenes is found. It is predicted that in the presence of weak bases and in aprotic solvents as well as in the gas phase, the nucleophilic substitution reaction involving p-halogen calix[6]arenes should proceed through diastereomeric transition states.