Synthesis of substituted 3-pyridinecarbonitriles with potential biological activity

Summary The synthesis of some 5-cyano-4-hydroxy-2-pyridone derivatives (3 a–c) by condensation of 3-aminocrotononitrile (1) with substituted diethylmalonates (2 a–c) is described. Reaction of3 a with phosphorus oxychloride yields 4,6-dichloro-3-pyridinecarbonitrile (7 a), which reacts with various nucleophiles to give substituted 3-pyridinecarbonitriles (8–10).See ref. [1]     

The early history of calixarene chemistry

The history of calixarene chemistry from the mid-thirties until 1978 is described.This paper is dedicated to the commemorative issue on the 50th anniversary of calixarenes.     

Synthesen von Heterocyclen, 83. Mitt.: Über Synthesen mit o-Aminophenylglyoxal-dimethylacetal

Zusammenfassung o-Aminophenylglyoxal-dimethylacetal (1) läßt sich mit Carbonylverbindungen, die eine -Methylengruppe enthalten, im Sinne einerFriedländer-Synthese zu Derivaten des Chinolin-4-aldehyds umsetzen. Bei 150–160° reagiert1 mit Acetessigester und Malonester unter Bildung des 3-Acetyl-(11) bzw. 3-Car-bäthoxy-4-dimethoxymethyl-carbostyrils (12). o-Acetaminophenylglyoxal-dimethylacetal (21) kann mit Na-Äthylat zum Carbostyril-4-aldehyd-dimethylacetal (22) cyclisiert werden; mit Cyanessigester kondensiert sich21 zum 3-Cyan-4-dimethoxy-methyl-carbostyril (24).

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o-Aminophenylglyoxal-dimethylacetal (1) has been condensed with several cyclic ketones, acetophenones, and with acetone to yield derivatives of quinoline-4-aldehyde.1 reacts with ethyl acetoacetate and diethyl malonate at 160° yielding 3-acetyl-(11) and 3-carbethoxy-4-dimethoxymethyl-carbostyril (12) respectively. o-Acetaminophenylglyoxal dimethyl acetal (21) undergoes ring closure to carbostyril-4-aldehyde dimethyl acetal (22), when treated with sodium ethoxide; the reaction of21 with ethyl cyanoacetate leads to 3-cyano-4-dimethoxymethyl-carbostyril (24).

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Synthesen von Heterocyclen, 119. Mitt.: Über Reaktionen des Salicylsäurechlorids mit aromatischen Thioamiden

Zusammenfassung Salicylsäurechlorid (1) reagiert mit aromatischen Thioamiden unter HCl- und H₂S-Abspaltung zu 4H-1,3-Benzoxazinonen (2–5), welche mit verd. HCl zu N-Acylsalicylsäureamiden (6–9) gespalten werden.

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Salicyloyl chloride (1) reacts with aromatic thioamides to 4H-1.3-benzoxazinones (2–5), which can be hydrolized with dil. HCl yielding N-acyl-salicyloyl-amides (6–9).

     

Synthesen von Heterocyclen, 80. Mitt.: Über ein durch H-Brücken stabilisiertes 2,5-Dihydropyrazin

Zusammenfassung 3-Amino-4-hydroxycumarin (4), welches durch katalyt. Reduktion von 3-Phenylazo-4-hydroxycumarin (1) in 92proz. Ausb. zugänglich ist, wird beim Erhitzen mit 2n-NaOH in 3,6-Bis-(2-hydroxyphenyl)-2,5-dihydropyrazin (10) übergeführt. Die Dehydrierung von10 mit Pd liefert das entsprechende Pyrazin14, das auch aus dem o-Hydroxyphenylglyoxal-phenylhydrazon (13) gewonnen werden kann. Die Reduktion von10 mit Na/Butanol führt zum Piperazin18, die Reaktion mit Ac₂O zum 1,4-Dihydropyrazinderivat17.

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3-Amino-4-hydroxycoumarin (4), obtained in 92% yield by the catalytic hydrogenation of 3-phenylazo-4-hydroxycoumarin (1), is readily converted by refluxing in 2N-NaOH to 3,6-bis-(2-hydroxyphenyl)-2.5-dihydropyrazine (10). The dehydrogenation of10 with a Pd catalyst yields the corresponding pyrazine14, which can also be obtained from the o-hydroxyphenylglyoxal-phenylhydrazone (13). The reduction of10 with sodium in butanol yields the known 2.5-bis(2-hydroxyphenyl)-piperazine (18); the reaction of10 with acetic anhydride leads by isomerization to the 1,4-diacetyl-3,6-bis(2-acetoxyphenyl)-1.4-dihydropyrazine (17).

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Synthese von Indolen und Isochinolonen aus Phenylmalonylheterocyclen

A new synthesis of the indole system has been achieved by chclodehydrogenation of amino phenylmalonate heterocycles. Thus, the 4-amino coumarins1 a,b or the 4-amino-2-quinolones1 c–g are converted to the indoles2 with palladium on charcoal in boiling diphenyl ether. The reaction of the aminocompounds1 with diphenyl carbonate yields the fused polycyclic isoquinolones4.

     

Traceless solid-phase synthesis of bicyclic dihydropyrimidones using multidirectional cyclization cleavage

Solid-phase and solution-phase protocols for the synthesis of furo[3,4-d]pyrimidines, pyrrolo[3,4-d]pyrimidines, and pyrimido[4,5-d]pyridazines are reported. The multistep solid-phase sequence involves the initial high-speed, microwave-promoted acetoacetylation of hydroxymethylpolystyrene resin with methyl 4-chloroacetoacetate. The immobilized 4-chloroacetoacetate precursor was subsequently subjected to three-component Biginelli-type condensations employing urea and a variety of aromatic aldehydes. The resulting 6-chloromethyl-functionalized resin-bound dihydropyrimidones served as common chemical platforms for the generation of the desired heterobicyclic scaffolds using three different traceless cyclative cleavage strategies. The corresponding furo[3,4-d]pyrimidines were obtained by microwave flash heating in a rapid, thermally triggered, cyclative release. Treatment of the chloromethyl dihydropyrimidone intermediates with a variety of primary amines followed by high-temperature microwave heating furnished the anticipated pyrrolo[3,4-d]pyrimidine scaffolds via nucleophilic cyclative cleavage. In a similar way, reaction with monosubstituted hydrazines resulted in the formation of pyrimido[4,5-d]pyridazines. All compounds were obtained in moderate to good overall yields and purities.     

Microwave-assisted multistep synthesis of functionalized 4-arylquinolin-2(1H)-ones using palladium-catalyzed cross-coupling chemistry

[reaction: see text] Biologically active 4-aryl-3-alkenyl-substituted quinolin-2(1H)-ones have been synthesized in a short and concise manner employing readily available 4-hydroxyquinolin-2(1H)-ones as intermediates. Key steps in the synthesis include the derivatization of the quinolin-2(1H)-one cores using palladium-catalyzed Suzuki and Heck reactions, installing the 4-aryl and 3-alkenyl substituents. All synthetic transformations (six steps) required for the synthesis of the desired target quinolin-2(1H)-one were carried out using controlled microwave-assisted organic synthesis.     

Synthesen von Heterocyclen, 95. Mitt.: Chinolizine und Indolizine I: Eine Synthese von 2-Hydroxychinolizinonen-(4)

Zusammenfassung An der Methylgruppe substituierte -Picoline, insbesondere 2-Pyridylessigsäurederivate, reagieren mit unsubstit. oder monosubstit. Malonsäure-bis-trichlorphenylestern, Malonsäurechloriden oder Kohlensuboxid zu 2-Hydroxychinolizinonen-(4), die katalytisch zu 2-Hydroxy-6,7,8,9-tetrahydrochinolizinonen-(4) hydriert werden können.

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2-Alkylpyridines, especially derivatives of 2-pyridineacetic acid, react with unsubstituted and monosubstituted 2.4.6-trichlorophenyl malonates or malonyl chlorides or C₃O₂ to derivatives of 2-hydroxy-quinolizin-4-one. These compounds are hydrogenated in acetic acid in the presence of palladium to 2-hydroxy-6.7.8.9-tetrahydro-quinolizin-4-ones.

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Mit 2 Abbildungen.

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Herrn Prof. Dr.F. Wessely zum 70. Geburtstag gewidmet.     

Benzimidazole condensed ring systems,III . Synthesis of some substituted 2,3-dihydrocyclopenta-1H-[4′,5′: 2,3]pyrido[1,2-a]benzimidazole-11-carbonitriles

Summary The synthesis of compound3 by condensing 1H-benzimidazole-2-acetonitrile (1) with ethyl cyclopentanone-2-carboxylate (2) in the presence of ammonium acetate is described. Methylation of3 with trimethyl phosphate yielded the N-methyl derivative4. Methods for converting3 to some of its related derivatives in which the carbonyl function was replaced by Cl, N₃ and amines are also reported.

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Kondensierte Ringsysteme des Benzimidazols, 3. Mitt.. Synthese von substituierten 2,3-Dihydrocyclopenta[4,5:2,3]pyrido[1,2-a]benzimidazol-11-carbonitrilen

Zusammenfassung Die Synthese der tetracyclischen Verbindung3 durch Kondensation von 1H-Benzimidazol-2-acetonitril (1) mit Cyclopentanon-2-carbonsäureester (2) in Gegenwart von Ammonacetat wird beschrieben. Die Methylierung von3 mit Trimethylphosphat liefert das N-Methylderivat4. Die Sauerstoffunktion in3 kann durch Chlor, Azid und Aminogruppen ersetzt werden.