Atef M. Amer

[3+2]-cycloadditions of 1-Aza-2-azoniaallene cations to multiple bonds

Abstract Hydrazones of ketones 1, are transformed into 1-chloroalkylazo compounds, 2, which react with Lewis acids to give transient 1-aza-2-azoniaallene salts, 3. The cations 3 react with with acetylenes, olefins, isocyanates, carbodiimides, and nitriles under [3+2]-cycloadditions. The cycloadducts undergo consecutive reactions, e.g. [1,2]-shifts of alkyl groups.

Stereospecific synthesis of the enantiomers of nicotinylalanine, a neuroprotecting agent

Abstract Stereospecific synthesis of the title compounds has been achieved in >95% ee by use of palladium-catalyzed cross-coupling of S- and R-(3-benzyloxycarbonyl-5-oxo-4-oxazolidinyl)-acetyl chloride, respectively, with 3-trimethylstannyl pyridine at room temperature.

On the Synthesis of Pyrazino[2,3-b]phenazine and 1H-Imidazo[4,5-b]phenazine Derivatives

Summary. Several pyrazino[2,3-b]phenazine derivatives were prepared by the reaction of 2,3-diaminophenazine with different 1,2-diketones. Nucleophilic substitution of 2,3-dibromomethyl-pyrazino[2,3-b]phenazine with propanol, morpholine, and potassium thiocyanate gave 2,3-bis-(propoxymethyl)-pyrazino[2,3-b]phenazine, 2,3-bis-(4-morpholinylmethyl)-pyrazino[2,3-b]phenazine, and 2,3-bis-(cyanosulfanylmethyl)-pyrazino[2,3-b]phenazine. 2-Aryl-1H-imidazo[4,5-b]phenazine derivatives were synthesized by a one-pot reaction of 2,3-diaminophenazine with different aromatic aldehydes or acids. Reaction of 2,3-diaminophenazine with acetic anhydride and formic acid afforded 1H-imidazo[4,5-b]phenazine and 2-methyl-1H-imidazo[4,5-b]phenazine. Chemical and spectroscopic evidences for the product structures of the new compounds are presented.Zusammenfassung. Einige Pyrazino[2,3-b]phenazinderivate wurden durch Reaktion von 2,3-Diaminophenazin mit verschiedenen 1,2-Diketonen dargestellt. Nucleophile Substitution von 2,3-Dibrommethyl-pyrazino[2,3-b]phenazin mit Propanol, Morpholin und Kaliumthiocyanat ergab 2,3-Bis(propoxymethyl)-pyrazino[2,3-b]phenazin, 2,3-Bis-(4-morpholinylmethyl)-pyrazino[2,3-b]phenazin und 2,3-Bis-(cyanosulfanylmethyl)-pyrazino[2,3-b]phenazin. 2-Aryl-1H-imidazo[4,5-b]phenazinderivate wurden in einer Eintopfreaktion aus 2,3-Diaminophenazin mit verschiedenen aromatischen Aldehyden oder Carbonsäuren hergestellt. Reaktion von 2,3-Diaminophenazin mit Essigsäureanhydrid oder Ameisensäure lieferte 1H-Imidazo[4,5-b]phenazin und 2-Methyl-1H-imidazo[4,5-b]phenazin. Chemische und spektroskopische Nachweise für die Struktruren der neuen Verbindungen werden mitgeteilt.

On condensation reactions of aceanthrene quinone : Novel heterocycles

Summary. It was found that aceanthrene quinone can be condensed with ethylenediamine, 1,2-diaminobenzene, 4-nitro-1,2-diaminobenzene, 1,2-diaminoanthrene quinone, and 4,5,6-triaminopyrimidine derivatives to give aceanthryleno[1,2-b]pyrazine and aceanthryleno[1,2-g]pteridine derivatives. Condensation of aceanthrene quinone with 2-aminoguanidine, semicarbazide, and thiosemicarbazide yielded aceanthryleno[1,2-e]triazines, condensation with 6-hydrazinopyrimidine derivatives gave 3,4-aceanthrylenopyrimido[4,5-c]pyridazines. Reaction of aceanthrene quinone with 2-cyanoethanoic acid hydrazide afforded 10,11-dihydro-10-oxo-aceanthryleno[1,2-c]pyridazine-9-carbonitrile. Treatment of aceanthrene quinone with malononitrile and hydrazine hydrate resulted in 10-aminoaceanthryleno[1,2-c]pyridazine-9-carbonitrile. The antibacterial effects of the prepared compounds were tested. Three of the compounds were tested against 60 cancer types.

Syntheses of C- and N-nucleosides from 1-aza-2-azoniaallene and 1,3-diaza-2-azoniaallene salts

C-Nucleosides are prepared by cycloaddition of 1-aza-2-azoniaallene salts 2 and 1,3-diaza-2-azoniaallene salts 5 to the triple bonds of a glycosylalkyne and of glycosyl cyanides. Thus, the glucosylalkyne 7 reacts with salts 5 to give the 4-glucosyl-1,2,3-triazolium salt 8. From the galactosyl cyanide 9, the ribofuranosyl cyanide 13, and several 1-aza-2-azoniaallene salts 2 the glycosyl-1,2,4-triazoles 11, 15, 17 are obtained. Deacylation affords the free C-nucleosides 12, 16, 18. Cycloaddition to the CS double bond of the glucosyl isothiocyanate 19 furnishes glucosylimino-1,3,4-thiaziazoles 20–22. A new method for the preparation of the isothiocyanate 19 is described.

Synthesis and Reactions of 1-Azo-2-azonia-allene Salts Derived from Pyridine Derivatives

Summary. The 1-aza-2-azonia-allene salts prepared from 3-acetyl- or 3-benzoyl-pyridine via the corresponding hydrazone and α-chloroaryl-azo derivatives react with propionitrile to afford the corresponding 3-(3-pyridyl)-1,2,4-triazolium salts. The intramolecular cyclization products could be only isolated as the main products if the intermediate α-chlorophenyl-azo derivatives prepared from 4-benzoyl pyridine were treated with SbCl5 in presence or absence of propionitrile. Also, only 3-methyl-1,2,3-triazolo[1,5-a]pyridinium salts were obtained by reaction of the cumulene prepared from 2-acetyl-pyridine with or without propionitrile in good yields. Treatment of 3-pyridylindazolium hexachloroantimonates and 3-methyl-1,2,3-triazolo[1,5-a]pyridinium salts with Na2CO3 gave 3-pyridylindazoles and 3-methyl-1,2,3-triazolo[1,5-a]pyridine..Zusammenfassung. Die 1-Aza-2-azoniasalze, die aus 3-Acetyl- oder 3-Benzoylpyridin über die entsprechenden Hydrazone und α-Chlorazoderivate dargestellt wurden, reagieren mit Propionitril zu den entsprechenden 3-(3-Pyridyl)-1,2,4-triazoliumsalzen. Intramolekulare Cyklisierungsprodukte konnten nur isoliert werden, wenn die intermediären α-Chlorphenylazoderivate aus Benzoylpyridin abgeleitet wurden und mit SbCl5 mit oder ohne Propionitril umgesetzt wurden. Ebenso wurden im Fall der Reaktion des Cumulens aus 2-Acetylpyridin mit oder ohne Propionitril nur die 3-Methyl-1,2,3-triazolo[1,5-a]pyridiniumsalze in guten Ausbeuten erhalten. Behandlung von 3-Pyridylindazoliumhexachloroantimonaten mit Na2CO3 ergab 3-Pyridylindazole und 3-Methyl-1,2,3-triazolo[1,5-a]pyridine..

Pyridazine derivatives and related compounds. Part 141. Photolysis of 3-diazo-4,5-diphenylpyrazolo[3,4-c]pyridazine

The photochemistry of 3-diazopyrazolopyridazine has been investigated. The irradiation of 3-diazo-4,5-diphenylpyrazolo[3,4-c]pyridazine in various solvents forms a carbene intermediate, which transforms into 3-substituted derivatives. For photolysis in the presence of acetylacetone or ethyl acetoacetate the coupling reactions which occur at the methylene group are faster than carbene formation, and can lead to direct cyclisation into condensed 1,2,4-triazines. Photolysis in the presence of diethyl malonate forms an acyclic hydrazone.

On the Chemistry of Cinnoline I. Synthesis and Reactions of (4-Amino-cinnolin-3-yl)-p-tolyl- methanones

Summary. The synthesis of a series of (4-Amino-cinnolin-3-yl)-p-tolyl-methanones from aryl-hydrazonomalononitrile in a one step procedure is reported. The (4-amino-cinnolin-3-yl)-p-tolyl-methanones could be annelated to the corresponding 1,2-dihydro-4-(p-tolyl)-2-oxopyrido[3,2-c]cinnoline derivatives via (4-acetamido-cinnolin-3-yl)-p-tolyl-methanones. Treatment of 1,2-dihydro-9-methyl-4-(p-tolyl)-pyrido[3,2-c]cinnoline-2-one with POCl3 and P2S5 gave 2-chloro-9-methyl-4-(p-tolyl)-pyrido[3,2-c]cinnoline and 1,2-dihydro-9-methyl-4-(p-tolyl)-pyrido[3,2-c]cinnoline-2-thione. Treatment of the ketone with malononitrile afforded 2-amino-3-cyano-9-methyl-4-(p-tolyl)-pyrido[3,2-c]cinnoline. Using these ketones, a facile and convenient route towards substituted pyrimidino[5,4-c]-cinnolines was developed. Chemical and spectroscopic evidences for the structures of the new compounds are presented.Zusammenfassung. Die Synthese einer Reihe von (4-Amino-cinnolin-3-yl)-p-tolyl-methanonen aus Arylhydrazonomalonitrilen in einem Schritt wird beschrieben. Die Edukte wurden über die (4-Acetamido-cinnolin-3-yl)-p-tolyl-methanone zu den entsprechenden 1,2-Dihydro-4-(p-tolyl)-2-oxopyprido[3,2-c]cinnolinderivaten anelliert. Behandlung der 1,2-Dihydro-9-methyl-4-(p-tolyl)-pyrido[3,2-c]cinnolin-2-one mit POCl3 bzw. P2S5 ergab 2-Chlor-9-methyl-4-(p-tolyl)-pyrido[3,2-c]cinnolin und 1,2-Dihydro-9-methyl-4-(p-tolyl)-pyrido[3,2-c]cinnolin-2-thion. Umsetzung dieses Ketons mit Malonitril lieferte 2-Amino-3-cyano-9-methyl-4-(p-tolyl)-pyrido[3,2-c]cinnolin. Mit Hilfe dieser Edukte wurde eine einfache Route zu substituierten Pyrimidino[5,4-c]cinnolinen eröffnet. Chemische und spektroskopische Evidenzen für die Struktur der neuen Verbindungen werden mitgeteilt.

Synthesis of 1,2,4-triazolium salts: Reaction of 1-azo-2-azonia-allene salts with nitriles

SummaryAlkyl ketone hydrazones1 are oxidized withtert-butylhypochlorite to give geminal chloro azo compounds2. These react with SbCl5 to give 1-aza-2-azonia-allene salts3 as reactive intermediates which are intercepted with nitriles to yield 3H-1,2,4-triazolium salts5. In most cases these salts rearrange spontaneously to form 1H-triazolium salts6. Hydrolysis of6e–g by NaOH provide bases7a–c, which react with picric acid to give 1H-pyrazolium picrates8.ZusammenfassungAlkylketonhydrazone1 werden durchtert-Butylhypochlorit zu geminalen Chlorazoverbindungen2 oxidiert. Diese reagieren mit SbCl5 zu 1-Aza-2-azonia-allensalzen3, welche mit Nitrilen unter Bildung von 3H-1,2,4-Triazoliumsalzen5 abgefangen werden. In den meisten Fällen lagern diese spontan zu 1H-Triazoliumsalzen6 um. Hydrolyse von6e–g mit NaOH führt zu den Basen7a–c, welche mit Pikrinsäure 1H-Pyrazoliumpikrate8 bilden.