The reaction of 2-picoline N-Oxide with o-substituled benzoates and lsatoic anhydrides

The reaction of 2-picoline N-Oxide anion with o-substituted henzoates and isatoic anhydrides to give synthetically useful l-(2-methoxyphenyl)-2-(2-pyridinyl)ethanone N-oxides, I-(2-hydroxy-phenyJ)-2-(2-pyridinyl)ethanone N-oxides and I -(2-arninopheny])-2-(2-pyridinyl)ethanone N-oxides is described.     

ortho-Alkylation of Pyridine N-Oxides with Alkynes by Photocatalysis: Pyridine N-Oxide as a Redox Auxiliary

A photocatalyzed ortho-alkylation of pyridine N-oxide with ynamides and arylacetylenes has been developed, which yields a series of α-(2-pyridinyl) benzyl amides/ketones. Mechanistic studies, including electrochemical studies, radical-trapping experiments, and Stern–Volmer fluorescence quenching studies demonstrate that pyridine N-oxide serves as both a redox auxiliary and radical acceptor to achieve the mild photocatalytic single-electron oxidation of carbon–carbon triple bonds with the generation of a cationic vinyl radical intermediate.     

Synthesis and reactions of 1-[1-oxido-2-(3,4)-pyridinyl]-2-methyloxiranes with nitrogen nucleophiles

Reaction of 2(3,4)-pyridinecarboxaldehydes (5) with ethylidenetriphenylphosphorane afford a mixture of stereoisomers Z-( 6 ) and E-1-[2(3,4)-pyridinyl]-1-propenes ( 7 ). m-Chloroperbenzoic acid oxidation of 6 and 7 yields a 60:40 mixture of Z-( 8 ) and E-1-[1-oxido-2(3,4)-pyridinyl]-2-methyloxiranes ( 9 ). The regiospecific reaction of Z-isomers 8a-c with cyclic amines as piperidine give rise to threo-1-hydroxy-1-[1-oxido-2(3,4)-pyridinyl]-2-(1-piperidino)propanes ( 10 ) while the E-isomer 9a yields erythro- 11 . On tho other hand, the E-isomers 9b and 9c having 1-oxido-3(4)-pyridinyl substituents afford erythro- 12 resulting from attack by piperidine at C-1 of the oxirane. Reductive deoxygenation using 10% palladium on charcoal and hydrogen gas effectively removed the N-oxide substituent from the threo- 10 and erythro- 11 β-aminoalcohols. Dilute solution ir spectroscopy indicated the existance of strong intramolecular hydrogen bonding in the β-aminoalcohols 10 and 11 . The assignment of relative configuration of diastereoisomers 10 and 11 was based on the magnitude of the vicinal coupling constant J where J threo is greater than J erythro.     

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.     

S<Stack><Subscript>N</Subscript><Superscript>H</Superscript></Stack> Reaction of lithiated nitronyl nitroxide with quinoline <Emphasis Type="Italic">N</Emphasis>-oxide

The S_N^H reaction of lithiated 4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-1-oxyl 3-oxide with quinoline N-oxide affords 4,4,5,5-tetramethyl-2-(1-oxidoquinolin-2-yl)-4,5-dihydro-1H-imidazole-1-oxyl 3-oxide.     

The deoxydative substitution reactions of nicotinamide and nicotinic acid N-oxides by 1-adamantanethiol in acetic anhydride

The reaction of nicotinamide N-oxide with 1-adamantanethiol in acetic anhydride yielded a mixture of 2-and 6-(1-adamantylthio)nicotinamides (49%, in the ratio of 24:1) and 2-, 5-, and 6-(1-adamantylthio)nicotino-nitriles (18%, in the ratio of 79:1:20). From a reaction of nicotinic acid N-oxide with 1-adamantanethiol, there was isolated 2-(1-adamantylthio)nicotinic acid as the only sulfide in 23% yield. Carbon? sulfur bond cleavage took place when 2-(1-adamantylthio)nicotinic acid, or the corresponding amide or nitrile, were boiled with concentrated hydrochloric acid to furnish 2-mercaptonicotinic acid and 1-chloroadamantane, quantitatively. The reaction of nicotinamide N-oxide alone in acetic anhydride at 135° formed N-acetyl-2-hydroxynicotinamide (61%), 2-hydroxynicotinonitrile (0.5%) and N,N-diacetyl-2-acetoxynicotinamide (0.8%).     

Synthesis of mesoionic triazolo[4,3-a]quinoxalines

The reaction of 6-chloro-2-(1-methylhydrazino)quinoxaline 4-oxide 1 or 6-chloro-2-(1-methylhydrazino)-quinoxaline 5 with phenyl isothiocyanate under reflux in N,N-dimethylformamide gave 7-chloro-3-methyl-1,2,4-triazolo[4,3-a]quinoxalin-3-ium-1-thioate 4 , which was also obtained by refluxing of 6-chloro-2-[1-methyl-2-(N-phenylthiocarbamoyl)hydrazino]quinoxaline 4-oxide 2b or 6-chloro-2-[1-methyl-2-(N-phenylthiocarbamoyl)hydrazino]quinoxaline 6 in N,N-dimethylformamide.     

Unusual photorearrangement of 1,7-disubstituted 7-azabenzonorbornadiene

1-(11-Benzoyl-11-azatricyclo[6.2.1.0^2,7]undeca-2,4,6,9-tetraen-1-yl)ethanone was synthesized by cycloaddition of 2-acetyl-N-benzoylpyrrole to benzyne. Direct photolysis of 1-(11-benzoyl-11-azatricyclo-[6.2.1.0^2,7]undeca-2,4,6,9-tetraen-1-yl)ethanone in benzene gave N-(4-acetylnaphthalen-1-yl)benzamide. The formation of this product is discussed in terms of radical-stabilizing and destabilizing effect of electron-withdrawing group in the formation of cyclopropane ring. Published in Russian in Zhurnal Organicheskoi Khimii, 2009, Vol. 45, No. 4, pp. 626–629. The text was submitted by the authors in English.     

Synthesis of 1-{4a,6-dimethyl-4a,9a-dihydropyrano-[3,4-<Emphasis Type="Italic">b</Emphasis>]indol-9(1<Emphasis Type="Italic">H</Emphasis>)-yl}ethanone

Heating of the bromination product of 4-methyl-3,6-dihydro-2H-pyran with 4-toluidine or 2-bromo-4-methylamiline in triethylamine gave 4-methyl-N-(4-methylphenyl)- and N-(2-bromo-4-methylphenyl)-4-methyl-3,6-dihydro-2H-pyran-3-amines which were converted into the corresponding amides by reaction with bromo- or chloroacetyl chloride. 1-{4a,6-Dimethyl-4a,9a-dihydropyrano[3,4-b]indol-9(1H)-yl} ethanone was synthesized in good yield by heating N-(2-bromo-4-methylphenyl)-N-(4-methyl-3,6-dihydro-2Hpyran-3-yl)acetamide in boiling toluene in the presence of palladium(II) acetate, triphenylphosphine, copper(II) acetate, triethylamine, and potassium carbonate.     

Furopyridines. XVII . Cyanation,chlorination and nitration of furo[3,2-b]pyridine N-oxide

The N-oxide 2 of furo[3,2-b]pyridine ( 1 ) was cyanated by the Reissert-Henze reaction with potassium cyanide and benzoyl chloride to give 5-cyano derivative 3 , which was converted to the carboxamide 4 , carboxylic acid 5 , ethyl ester 6 and ethyl imidate 8 . Chlorination of 2 with phosphorus oxychloride yielded 2-9a , 3- 9b , 5- 9c and 7-chloro derivative 9d . Reaction of 9d with sodium methoxide, pyrrolidine, N,N-dimethylformamide and ethyl cyanoacetate afforded 7-methoxy- 10 , 7-(1-pyrrolidyl)- 11 and 7-dimethylaminofuro[3,2-b]pyridine ( 14 ) and 7-(1-cyano-1-ethoxy-carbonyl)methylene-4,7-dihydrofuro[3,2-b]pyridine ( 12 ). Nitration of 2 with a mixture of fuming nitric acid and sulfuric acid gave 2-nitrofuro[3,2-b]pyridine N-oxide ( 15 ).     

Transformations of 3-nitropyridin-4(1<Emphasis Type="Italic">H</Emphasis>)-one and 1-Methyl-3-nitropyridin-4(1<Emphasis Type="Italic">H</Emphasis>)-one in reaction with hydrazine

Hydrazinolysis of 3-nitropyridin-4(1H)-one and its N-methyl derivative leads to the formation of 1-(1H-pyrazol-3-yl)ethanone hydrazone whose structure was confirmed by independent synthesis from authentic 3-acetyl-1H-pyrazole and comparison of the IR and ¹H NMR spectra. Oxidation of 1-(1H-pyrazol-3- yl)ethanone hydrazone with potassium permanganate gave 1H-pyrazole-3-carboxylic acid.     

Furopyridines. XXIV. Nitration,chlorination, acetoxylation and cyanation of 2,3-dihydrofuro[2,3-b]-, -[3,2-b]-, -[2,3-c]- and -[3,2-c]pyridine N-Oxides

Nitration of 2,3-dihydrofuro[3,2-b]- N-oxide 3b and -[2,3-c]pyridine N-oxide 3c afforded the nitropyridine compounds 4b, 5b and 6 from 3b and 4c, 5c, 5′c and 7 from 3c , while -[2,3-b]- N-oxide 3a and -[3,2-c]pyridine N-oxide 3d did not give the nitro compound. Chlorination of 3b and 3c with phosphorus oxychloride yielded mainly the chloropyridine derivatives 15b, 15′b from 3b and 15c and 15′c from 3c , whereas 3a and 3d gave pyridine derivatives formed through fission of the 1–2 ether bond of the furo-pyridines 13a , 14 and 13d . Acetoxylation of 3b and 3c gave 3-acetoxy derivatives 18b and 18c and the parent compound 1b and 1c . Acetoxylation of 3a yielded compounds formed through fission of the 1–2 bond 16 and 17 and 3d gave furopyridones 19 and 19 ′. Cyanation of 3b and 3c yielded mainly the cyanopyridine compounds 20b, 20c and 20′c . Cyanation of 3a and 3d gave the cyanopyridine compounds 20a , 20d and 20′d accompanying formation of the pyridine derivatives 21a, 21d and 21′d .     

Thermochemical study of the trans- and cis-isomeric forms of 4-(4-methoxystyryl)pyridine N-oxide

The trans and cis form of 4-(4-methoxystyryl)pyridine N-oxide were studied. The spectral characteristics of cis-4-(4-methoxystyryl)pyridine N-oxide were determined in acetonitrile. The melting and thermal decomposition processes of the trans and cisforms of 4-(4-methoxystyryl)pyridine N-oxide were studied by thermochemical methods. It was establish that the thermal decomposition of 4-(4-methoxystyryl)pyridine N-oxide begins with the cleavage of the bond between the pyridine and benzene rings.

     

Nitration of 5,6,7,8-tetrahydro-5,8-methanoisoquinoline N-oxide with other aromatic substitutions. Isolation and mutagenicity of an α-nitropyridine N-oxide

Treatment of 5,6,7,8-tetrahydro-5,8-methanoisoquinoline N-oxide ( 2 ) with fuming nitric acid afforded 3-nitro-5,6,7,8-tetrahydro-5,8-methanoisoquinoline N-oxide ( 3 ), an example of formation of an α-nitropyridine N-oxide derivative by nitration of N-oxides. Further reaction of 3 resulted in deoxygenation giving 3-nitro-5,6,7,8-tetrahydro-5,8-methanoisoquinoline ( 4 ). No aromatic nitration was observed by similar treatment of 5,6,7,8-tetrahydro-5,8-methanoisoquinoline ( 1 ) or 5,6,7,8-tetrahydroisoquinoline N-oxide ( 11 ). Some other aromatic substitutions with 1 and 2 were caried out to obtain mainly the 3-substituted derivatives. Significant mutagenicity of 3 is briefly reported.     

Pseudolycorine N-oxide,a new N-oxide from Narcissus tazetta

Abstract

A new N-oxide, Pseudolycorine N-oxide (1) was characterised along with eleven known alkaloids homolycorine (2), O-methylmaritidine (3), 8-O-demethylhomolycorine (4), homolycorine N-oxide (5), lycorine (6), narciclasine (7), pseudolycorine (8), ungeremine (9), 8-O-demethylmaritidine (10), zefbetaine (11) and lycorine N-oxide (12), from Narcissus tazetta. Their structures were established on the basis of spectroscopic data analysis. The extract, fractions and isolated compounds were screened for in vitro cytotoxicity against two human cancer cell lines, human cervical cancer (SiHa) and human epidermoid carcinoma (KB) cells. The study demonstrated the cytotoxic potential of extract and its chloroform and n-butanol fractions. Further, the results revealed the bioactive potential of narciclasine, pseudolycorine and homolycorine alkaloids. However, new N-oxide (1) was not active against these cell lines.     

Reaction of N-(2-pyridylmethyl)-3,5-dimethylbenzamide and N-(3-pyridylmethyl)-3,5-dimethylbenzamide N-oxides with acetic anhydride

As a continuation of our work on the reaction of N-pyridylmethyl-3,5-dimethylbenzamide N-oxides with acetic anhydride, we now report a study of the reaction of N-(2-pyridylmethyl)-3,5-dimethylbenzam.de N-oxide ( 5 ) and N-(3-pyridylmethyl)-3,5-dimethylbenzamide N-oxide ( 6 ) with acetic anhydride. Compound 5 gave N,N′-di(3,5.dimethylbenzoyl)-1,2-di(2.pyridyl)ethenediamine ( 7 ) and 3,5-dimethylbenzamtde ( 8 ). Compound 6 afforded three products formulated as 2-acetoxy-3-(3,5-dimethylbenzoylaminomethyl)pyridine ( 12 ), 3-(3,5-dimethylbenzoylaminomethyl)-2-pyridone ( 13 ) and 5-(3,5-dimethylbenzoylaminomethyl)-2-pyridone ( 14 ). Analytical and spectral data are presented which support the structures proposed.     

A novel hydrogen-bonding N-oxide–sulfonamide–nitro N—H…O synthon determining the architecture of benzenesulfonamide cocrystals

The structures of novel cocrystals of 4-nitropyridine N-oxide with benzenesulfonamide derivatives, namely, 4-nitrobenzenesulfonamide–4-nitropyridine N-oxide (1/1), C₅H₄N₂O₃·C₆H₆N₂O₄S, and 4-chlorobenzenesulfonamide–4-nitropyridine N-oxide (1/1), C₆H₆ClNO₂S·C₅H₄N₂O₃, are stabilized by N—H…O hydrogen bonds, with the sulfonamide group acting as a proton donor. The O atoms of the N-oxide and nitro groups are acceptors in these interactions. The latter is a double acceptor of bifurcated hydrogen bonds. Previous studies on similar crystal structures indicated competition between these functional groups in the formation of hydrogen bonds, with the priority being for the N-oxide group. In contrast, the present X-ray studies indicate the existence of a hydrogen-bonding synthon including N—H…O(N-oxide) and N—H…O(nitro) bridges. We present here a more detailed analysis of the N-oxide–sulfonamide–nitro N—H…O ternary complex with quantum theory computations and the Quantum Theory of Atoms in Molecules (QTAIM) approach. Both interactions are present in the crystals, but the O atom of the N-oxide group is found to be a more effective proton acceptor in hydrogen bonds, with an interaction energy about twice that of the nitro-group O atoms.     

Synthesis and characterization of ruthenium p-cymene complexes bearing bidentate P–N and E–N ligands (E = S,Se) based on 2-aminopyridine

The syntheses and characterization of a series of cationic of Ru(II) halfsandwich complexes of the types [Ru(η⁶-p-cymene)(κ²(P,N)-PN)Cl]⁺ (PN = N-diphenylphosphino-2-aminopyridine, N-di-iso-propylphosphino-2-aminopyridine, 2-[(2-pyridyl)amino]dibenzo[d,f][1,2,3]dioxaphosphepine, N-(diisopropylphosphino)-2,6-diaminopyridine) and [Ru(η⁶-p-cymene)(κ²(E,N)-EN)Cl]⁺ (EN = N-(2-pyridinyl)amino-diphenylphosphine sulfide, N-(2-pyridinyl)amino-diisopropylphosphine sulfide, N-(2-pyridinyl)amino-diphenylphosphine selenide, N-(2-pyridinyl)amino-diisopropylphosphine selenide) is described. Some of these complexes were tested as precatalysts for the transfer hydrogenation of acetophenone to give 1-phenyl ethanol.     

The Constituents of Cananga odorata

Sixteen compounds, (+)-ushinsunine-β-N-oxide ( 1 ), cleistopholine ( 2 ), liriodenine ( 3 ), (-)-anonaine ( 4 ), (+)-nornuciferine ( 5 ), (+)-N-acetylnornuciferine ( 6 ), (-)-ushinsunine ( 7 ), (-)-norushinsunine ( 8 ), (-)-asimilobine ( 9 ), (+)-reticuline ( 10 ), N-trans-feruloyltyramine ( 11 ), β-sitosterol (12) and stigmasterol ( 13 ), lyscamine ( 14 ), (-)-anaxagoreine ( 15 ) and trans-cinnamic acid ( 16 ) were isolated from the methanolic extract of the Cananga odorata. Among them, 1 is a new stereoisomer of ushinsunine-β-N-oxide. The structures of these compounds were established by means of spectral experiments.     

Reactions of N,N'-Dimethyl-N,N'-bis(trimethylsilyl)methylphosphonic Diamide with Chloral and Chloromethyldimethylchlorosilane

N,N'-Dimethyl-N,N'-bis(trimethylsilyl)methylphosphonic diamide reacts with chloral to form 1,2,3-trimethyl-4,4-dichloro-5-trimethylsiloxy-1,3,2-diazaphospholidine 2-oxide and with chloromethyldi- methylchlorosilane to form 1,2,3,4,4-pentamethyl-1,3-diaza-2-phospha-4-silacyclopentane 2-oxide.