Carbon-nitrogen Bond Cleavage Research Articles

Novel diastereoisomers of ethylenediaminetetrapropionato-chromate(III). Part 1. Preparation and characterization

Hexadentate ethylenediaminetetraacetato-like chromate(III) complexes were prepared with ethylenediamine-N,N,N′,N′-tetrapropionate (edtp), (S)-propane-1,2-diamine-N,N,N′,N′-tetrapropionate [(S)-pdtp] and (1S,2S)-trans-cyclohexane-1,2-diamine-N,N,N′,N′-tetrapropionate [(SS)-cydtp] ligands. For each complex, QAE-Sephadex column chromatography demonstrated three isomers, which were characterized by 2H NMR and circular dichroism (CD) spectra to be novel diastereoisomers arising from a pairwise combination of two chiral ethylenic gauche conformations at the six-membered propionate rings. Two of the diastereoisomers were found to undergo thermal hydrolysis with anomalous carbon–nitrogen bond cleavage in aqueous solution to give diamine-tripropionato complexes and 3-hydroxypropionic acid.

Ultrasonic irradiation of p-nitrophenol in aqueous solution

The kinetics and mechanism of the sonochemical reactions of p-nitrophenol have been investigated in oxygenated aqueous solutions. In the presence of ultrasound (20 kHz, 84 W) p-nitrophenol was degraded primarily by denitration to yield NO_2^-, NO_3^-, benzoquinone, hydroquinone, 4-nitrocatechol, formate, and oxalate. These reaction products and the kinetic observations are consistent with a model involving high-temperature reactions of p-nitrophenol in the interfacial region of cavitation bubbles. The main reaction pathway appears to be carbon-nitrogen bond cleavage. Reaction with hydroxyl radical provides a secondary reaction channel. The average effective temperature of the interfacial region surrounding the cavitation bubbles was estimated to be T ≃ 800 K.

Synthesis of Nucleosides and Related Compounds. Part XX. Synthesis of Carbocyclic Nucleosides from 2-Azabicyclo(2.2.1)hept-5-en-3-ones: Sodium Borohydride-Mediated Carbon-Nitrogen Bond Cleavage of Five-and Six-Membered Lactams.

Various carbocyclic ribofuranosyl nucleosides were stereoselectively synthesized through a small number of steps from 2-azabicyclo[2.2.1]hept-5-en-3-ones by the use of sodium borohydride-mediated C-N bond cleavage as a key step. Ready availability of a novel synthetic precursor, (±)-4β-hydroxymethyl-1β-ureidocyclopentane-2α, 3α-diol [(±)-carbocyclic ribofuranosylurea], provides not only facile routes to carbocyclic robofuranosylpyrimidines, but also another route to the corresponding cyclopentylamine, (±)-1β-amino-4β-hydroxymethylcyclopentane-2α, 3α-diol [(±)-carbocyclic ribofuranosylamine], which is useful for the synthesis of the corresponding purine nucleosides.

Mechanism of carbon-nitrogen bond cleavage during amylamine hydrodenitrogenation over a sulphided NiMo/Al2O3 catalyst

By comparison of the hydrodenitrogenation rate of amylamine with those of neopentylamine and tert-amylamine over a conventional catalyst, it was evidenced that the hydrogen atoms of the carbon in the β position with respect to the nitrogen atom participate in the C-N bond cleavage. A detailed mechanism including the interaction with the catalyst is proposed for this reaction.

A novel base-catalyzed carbon-nitrogen bond fission in some heterocycles

Nitrogen heterocycles bearing a nonbasic nitrogen atom and other defined structural features as exemplified by 9,10-dimethoxy-3,4,6,7-tetrahydro-2H-pyrimido [6,1-a] isoquinoline-2,4-dione (1), 8-oxypseudopalmatine (22), 8-oxypseudoberberine (25), rutaecarpine (39), and related systems, on heating with excess sodium hydride in polar aprotic solvents, undergo a facile carbon-nitrogen bond cleavage reaction to give new nitrogen heterocycles with an arylvinyl group as one of the substituents

Barium Permanganate, Ba(MnO 4) 2, A Versatile and Mild Oxidizing Agent for Use Under Aprotic and Non-Aqueous Conditions

Barium Permanganate is an easily prepared, stable, and a versatile oxidation reagent. With this reagent different types of primary and secondary hydroxy compounds are converted to their carbonyl derivatives. Aldehydes could be transformed to their carboxylic acids. Benzylic chloride and bromides are converted to their aldehydes and carboxylic acids. Semicarbazide and 2,4-dinitrophenylhydrazine derivatives of benzylic carbonyl compounds undergo carbon-nitrogen bond cleavage selectively and yield the expected carbonyl compounds. p-Hydroquinone is converted to p-benzoguinone and aromatic amines to their azo compounds. Anthracene and phenanthrene produce their 9,10-quinones. Diphenyl acetylene and trans stilbene give benzil, and styrene produces benzaldehyde. Selective oxidations of secondary benzylic carbon-hydrogen bonds occur and the corres- ponding carbonyl compounds are produced in good yields.

Thermospray liquid chromatography/mass spectrometry of quaternary ammonium saltst

AbstractVarious esters of choline and carnitine have been shown to undergo fragmentation dependent on both the structures of the molecules and the vapor and block temperatures when subjected to thermospray ionization mass spectrometry. The fragments observed vary with the structure of the ester portion and the backbone of the molecules, and are consistent with the compounds undergoing three types of reactions: (1) carbon—nitrogen bond cleavage to tertiary amines and alkyl compounds, (2) hydrolysis of the ester linkage, forming alcohols and organic acids, and (3) deacylation of the molecules to form acids and the corresponding quaternary alkene. The general applicability of the carbon—nitrogen bond cleavage mechanism was studied with other classes of quaternary compounds, but the sole products consistently detected for pyridinium, benzyldimethyldodecylammonium and tetraalkylammonium salts were amines. The fragments observed for the esters of choline and carnitine and also the anticholinergic 2,2‐diphenyl‐4‐diisopropylaminobutyramide methiodide suggest that the mechanism of the thermospray fragmentation pathway is similar to that of the Hofmann elimination reaction.

Stereospecific synthesis of carbocyclic nucleosides from 2-azabicyclo-[2.2.1]heptan-3-ones via sodium borohydride mediated carbon-nitrogen bond cleavage

New synthons for carbocyclic nucleosides have been synthesized from 2-azabicyclo[2.2.1]hept-5-en-3-one readily available from cyclopentadiene, through introduction of an electron-withdrawing substituent at the 2-position followed by reduction with sodium borohydride.

Isotopic probes of the argininosuccinate lyase reaction.

The mechanism of the argininosuccinate lyase reaction has been probed by the measurement of the effects of isotopic substitution at the reaction centers. A primary deuterium isotope effect of 1.0 on both V and V/K is obtained with (2S,3R)-argininosuccinate-3-d, while a primary 15N isotope effect on V/K of 0.9964 +/- 0.0003 is observed. The 15N isotope effect on the equilibrium constant is 1.018 +/- 0.001. The proton that is abstracted from C-3 of argininosuccinate is unable to exchange with the solvent from the enzyme-intermediate complex but is rapidly exchanged with solvent from the enzyme-fumarate-arginine complex. A deuterium solvent isotope effect of 2.0 is observed on the Vmax of the forward reaction. These and other data have been interpreted to suggest that argininosuccinate lyase catalyzes the cleavage of argininosuccinate via a carbanion intermediate. The proton abstraction step is not rate limiting, but the inverse 15N primary isotope effect and the solvent deuterium isotope effect suggest that protonation of the guanidino group and carbon-nitrogen bond cleavage of argininosuccinate are kinetically significant.

Acid-base catalysis in the argininosuccinate lyase reaction.

The pH variation of the kinetic parameters, Vmax and V/K, was examined for the forward and reverse reaction of bovine liver argininosuccinate lyase. In the forward reaction the Vmax profile showed one group that must be unprotonated for activity over the pH range 5-10. The V/K profile for argininosuccinate showed one group that must be unprotonated and two groups that must be protonated for activity. The Vmax profile for the reverse reaction showed only one group that must be protonated for activity. These results support the proposal that catalysis is facilitated in the forward reaction by a general base that abstracts a proton from C-3 of argininosuccinate and a general acid that donates a proton to the guanidinium nitrogen during carbon-nitrogen bond cleavage. The enzyme is completely inactivated by diethyl pyrocarbonate or a water-soluble carbodiimide at pH 6. These experiments suggest that a histidine and a carboxyl group are at or near the active site and are essential for catalytic activity. The observed shifts of the pH profiles of the forward reaction with temperature and organic solvent (25% dioxane) were also consistent with a histidine and carboxylate group.

Selective cleavage of carbon-nitrogen bonds with platinum

Hydrogenolyse de nitriles, d'amines primaires et secondaires, de composes nitro, d'heterocycles azotes et d'amides aromatiques

Carbon–nitrogen bond cleavage in 1-dimethylaminobut-2-yne and derived ligands in triruthenium and triosmium clusters

Dodecacarbonyltriruthenium reacts in refluxing cyclohexane with 1-dimethylaminobut-2-yne (MeC CCH2NMe2) to give good yields of the isomers [Ru3H(CO)9(µ3-MeCCCHNMe2)](1) and [Ru3H(CO)9-(µ3-MeCCHCNMe2)](2) which are related in stoicheiometry (although perhaps not in structure) to known complexes containing µ3-allenyl (R1CCCHR2) or diosmium-substituted µ3-allyl (R1CCHCR2) ligands. The osmium analogue of complex (1) is obtained similarly from [Os3(CO)12] but [Os3(CO)10-(MeCN)2] reacts at room temperature with the alkyne giving [Os3H(CO)9(µ3-MeCCCH2)] by C–N bond cleavage. Rotation about the C–N bond in complex (1) in chloroform solution is restricted but the rate is accelerated by the addition of small amounts of CF3CO2H while, in neat CF3CO2H, compound (1) is protonated to give [Ru3H2(CO)9(MeCCCHNMe2)]+ for which the rotation barrier is much higher. Neutralisation of acidic solutions of complex (1) gives up to 15% of the but-2-ynal compound [Ru3H2(CO)9(µ3-MeC2CHO)] by hydrolysis. Compound (1) is converted totally into (2) in refluxing hexane but in the presence of H2 hydrogenolysis of the C–N bond also occurs to give the compounds [Ru3H2(CO)9(µ3-MeC2Me)], [Ru3H(CO)9(µ3-MeCCCH2)] and [Ru3H(CO)9(µ3-MeCCHCH)].

Carbon–nitrogen bond cleavage in π-radicals derived by reduction of N-benzyl- and N-allyl-pyridinium salts

Certain 1-alkyl-2,4,6-trisubstituted pyridinium salts form π-radicals by electrochemical reduction which are stable in dimethylformamide on the scale of cyclic voltammetry, whereas the corresponding 1-benzyl and 1-allyl compounds undergo carbon–nitrogen bond cleavage at measured rates which are dependent on the size of the 2,6-substituents.

The electrochemical reduction of fluorenone imine, 9-aminofluorene, and several N-substituted derivatives in dimethylformamide

The cyclic voltammetric reduction of fluorenone imine (FlNH) and N-phenylfluorenone imine (FlNPh) in DMF occurs in successive one-electron steps. Although FlNH −. and FlNPh −. are relatively stable on the cyclic voltammetric time scale, they react on the coulometric time scale to give the corresponding amines in high yield. FlNH 2− and FlNPh 2− have half lives of less than 1 ms and react by abstracting a proton to give FlNH 2 − and FlNHPh −, respectively. Oxidation of FlNHPh − to FlNPh in the presence of potassium t-butoxide involves a kinetically-controlled anodic peak which arises from the catalytic oxidation of FlNHPh − by electrogenerated FlNPh and a second, irreversible, anodic peak at more positive potential which is assigned to the direct electrochemical oxidation of FlNHpH −. Electrocatalytic oxidation is not observed under analogous solution conditions in the FlNH 2 − system unless fluorenone azine anion radical is also present. FlHNH 2 −. and FlHNMe 2 −. decompose by carbon—nitrogen bond cleavage ( k =0.8 s −1 and 1.1 s −1, respectively, at −22°C and −51°C, respectively) to give an anionic fragment, presumably an amide, and a radical fragment, presumably FlH .. After reduction of the radical fragment to an anion by an unreacted anion radical, the amide abstracts a proton from the C 9 position of the starting material. FlH − also reacts by proton abstraction from starting material, but at a rate which is kinetically controlled on the cyclic voltammetric time scale. The oxidation of FlNMe 2 − to the corresponding cation occurs in successive, one-electron steps in the absence of FlH −. If reaction of the electrogenerated FlH − with FlHNMe 2 is incomplete when oxidation of FlNMe 2 − is effected, the intermediate radical, FlNMe 2 ., is interdicted by electrocatalytically formed FlH ..

The electrochemical reduction of fluorenone hydrazone, fluorenone fluorenylhydrazone, fluorenone azine and their benzophenone analogs in DMF

The electrochemical reductions of fluorenone hydrazone (Fl=NNH 2 ), fluorenone fluorenylhydrazone (FIHNHN=Fl), fluorenone azine (Fl=N−N=Fl) and benzophenone analogs have been studied at platinum cathodes in DMF−0.1 M(n -Bu) 4 NClO 4 in the absence and presence of an added proton donor. Fl=NNH 2 undergoes reduction to give an unstable anion radical which decomposes by an unidentified pathway to afford Fl=NH. The latter species is electroactive at the applied potential and is reduced to the corresponding amine, FlHNH 2 . Four electrons per molecule of Fl=NNH 2 are required for this process when electroreduction is effected in the presence of diethyl malonate (DEM), an electroinactive proton donor. Unreacted Fl=NNH 2 serves as the source of protons when electroreduction is conducted in the absence of DEM. Dual reaction channels are observed for the reduction of FlHNHN=Fl. If the corresponding anion radical is not protonated by either an added proton donor or unreacted starting material, decomposition occurs by carbon-nitrogen bond cleavage to give FlH 2 and Fl=NNH 2 as products. Reduction of the latter species occurs at the same potential as FlHNHN=Fl, ultimately affording FlHNH 2 . The reaction channel involving carbon-nitrogen bond cleavage is replaced by a pathway involving nitrogen-nitrogen bond cleavage in the presence of an added proton donor. The final reduction product by this route is FlHNH 2 . Fl=N−N=Fl is reduced stepwise and reversibly to its dianion in an aprotic medium. In the presence of a relatively strong proton donor such as hexafluoro-2-propanol, reduction gives FlHNHN=Fl. The redox behavior of the benzophenone analogs, Ph 2 C=N−N=CPh 2 , Ph 2 CHNHN=CPh 2 and Ph 2 C=NNH 2 , parallels that of their counterparts in the fluorene series.

The electrochemical reduction of fluorenone hydrazone, fluorenone fluorenylhydrazone, fluorenone azine and their benzophenone analogs in DMF

The electrochemical reductions of fluorenone hydrazone (Fl=NNH 2), fluorenone fluorenylhydrazone (FIHNHN=Fl), fluorenone azine (Fl=N−N=Fl) and benzophenone analogs have been studied at platinum cathodes in DMF−0.1 M(n-Bu) 4NClO 4 in the absence and presence of an added proton donor. Fl=NNH 2 undergoes reduction to give an unstable anion radical which decomposes by an unidentified pathway to afford Fl=NH. The latter species is electroactive at the applied potential and is reduced to the corresponding amine, FlHNH 2. Four electrons per molecule of Fl=NNH 2 are required for this process when electroreduction is effected in the presence of diethyl malonate (DEM), an electroinactive proton donor. Unreacted Fl=NNH 2 serves as the source of protons when electroreduction is conducted in the absence of DEM. Dual reaction channels are observed for the reduction of FlHNHN=Fl. If the corresponding anion radical is not protonated by either an added proton donor or unreacted starting material, decomposition occurs by carbon-nitrogen bond cleavage to give FlH 2 and Fl=NNH 2 as products. Reduction of the latter species occurs at the same potential as FlHNHN=Fl, ultimately affording FlHNH 2. The reaction channel involving carbon-nitrogen bond cleavage is replaced by a pathway involving nitrogen-nitrogen bond cleavage in the presence of an added proton donor. The final reduction product by this route is FlHNH 2. Fl=N−N=Fl is reduced stepwise and reversibly to its dianion in an aprotic medium. In the presence of a relatively strong proton donor such as hexafluoro-2-propanol, reduction gives FlHNHN=Fl. The redox behavior of the benzophenone analogs, Ph 2C=N−N=CPh 2, Ph 2CHNHN=CPh 2 and Ph 2C=NNH 2, parallels that of their counterparts in the fluorene series.

Arylation and alkylation of olefins by arylamines or hydrazines via the carbon-nitrogen bond cleavage in the presence of palladium(II) salts

Arylation and alkylation of olefins by arylamines or hydrazines via the carbon-nitrogen bond cleavage in the presence of palladium(II) salts

ChemInform Abstract: AN IMPROVED PROCEDURE FOR PREPARING 1‐AMINOPHOSPHONIC ESTERS AND 1‐AMINONITRILES BY CARBON‐NITROGEN BOND CLEAVAGE IN BENZYLIC CARBINAMINE DERIVATIVES

Chemischer InformationsdienstVolume 9, Issue 43 Organoelement Compounds ChemInform Abstract: AN IMPROVED PROCEDURE FOR PREPARING 1-AMINOPHOSPHONIC ESTERS AND 1-AMINONITRILES BY CARBON-NITROGEN BOND CLEAVAGE IN BENZYLIC CARBINAMINE DERIVATIVES J. LUKSZO, J. LUKSZOSearch for more papers by this authorR. TYKA, R. TYKASearch for more papers by this author J. LUKSZO, J. LUKSZOSearch for more papers by this authorR. TYKA, R. TYKASearch for more papers by this author First published: October 24, 1978 https://doi.org/10.1002/chin.197843275Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume9, Issue43October 24, 1978 RelatedInformation

Kinetics and mechanism of amide acetal hydrolysis. Carbon-oxygen vs. carbon-nitrogen bond cleavage in acid solutions

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetics and mechanism of amide acetal hydrolysis. Carbon-oxygen vs. carbon-nitrogen bond cleavage in acid solutionsRobert A. McClellandCite this: J. Am. Chem. Soc. 1978, 100, 6, 1844–1849Publication Date (Print):March 1, 1978Publication History Published online1 May 2002Published inissue 1 March 1978https://doi.org/10.1021/ja00474a031RIGHTS & PERMISSIONSArticle Views585Altmetric-Citations8LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (765 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Transition state activity coefficients in the acid-catalyzed hydrolysis of amides

The transition-state activity coefficient [Formula: see text] approach has been applied to the acid-catalyzed hydrolysis of benzamide and its N-alkyl derivatives. For all systems (with the exception of the N-tert-butyl derivative which reacts via carbon–nitrogen bond cleavage) a uniform type of medium dependence of [Formula: see text] is observed. The reaction shows a pronounced destabilization of S≠ over the whole region of acidity studied, practically identical to that found for the AAc-2 type of ester hydrolysis. This is interpreted in terms of an AoT2 mechanism of amide hydrolysis, that is the rate-determining formation of the oxonium-type tetrahedral intermediate from the O-protonated form of substrate conjugate acid.