Active Methine Group Research Articles

Ruthenium(II) nitro-nitroso-bis-{1-(alkyl)-2-(β-napthylazo)imidazole}: Synthesis, spectroscopy, electrochemistry and reactivity

Aquation of blue cis-trans-cis-[RuCl2(β-NaiR)2] (1) leads to the synthesis of solvento species, blue-violet cis-trans-cis-[Ru(OH2)2(β-NaiR)2](ClO4)2 (2), [β-NaiR = C10H7-N=N-C3H2-NN, abbreviated as N,N′-chelator, R = Me] that have been reacted with NaNO2 in warm EtOH resulting in violet dinitro complexes of the type, [Ru(NO2)2(β-NaiR)2] (3). The nitrite complexes are useful synthons of electrophilic nitrosyls, and on triturating the dinitro compounds with cone. HClO4 nitro-nitrosyl derivatives, [Ru(NO2)(NO)(β-NaiR)2]2+ (4) are isolated. The chemical oxidation of aqua complex (2) by excess aqueous eerie solution in 1 (N) H2SO4 leads to the spontaneous formation of a yellow colored species. The electrophilic behaviour of metal bound nitrosyl has been proved by reacting with a bicyclic ketone, camphor, containing an active methylene group and an arylhydrazone with an active methine group. The diazotization of the primary aromatic amines with a strongly electrophilic mononitrosyl complex in acetonotrile and dichloromethane solution was thoroughly studied. Electrocatalytic oxidation of benzyl alcohol was examined.

ChemInform Abstract: Synthesis of Dihydropyrroles and Tetrahydropyridines by the Cyclization of O-Methylsulfonyloximes Having an Active Methine Group.

ChemInform Abstract: Synthesis of Dihydropyrroles and Tetrahydropyridines by the Cyclization of O-Methylsulfonyloximes Having an Active Methine Group.

Synthesis, spectra and electrochemistry of dinitro-bis-2-(phenylazo)pyrimidine ruthenium(II). Nitro*#x2014;nitroso derivatives and reactivity of the electrophilic nitrosyl centreruthenium(II). Nitro*#x2014;nitroso derivatives and reactivity of the electrophilic nitrosyl centre

Silver-assisted aquation of bluecis-trans-cis-RuCl2(Raapm)2 (1a-1e) leads to the synthesis of solvento species, blue-violetcis-trans-cis-[Ru(OH2)2(Raapm)2](ClO4)2 [Raapm =p-R-C6H4-N=N-C4H3-NN, (2a-2e), abbreviated as N,N′-chelator, where N(pyrimidine) and N(azo) represent N and N′ respectively; R = H (a),p-Me (b),p-Cl (c),m-Me (d),m-Cl (e) that react with NO2 in warm EtOH to give violet dinitro complexes of the type, Ru(NO2)2(Raapm)2 (3a-3e). The nitrite complexes are useful synthons of electrophilic nitrosyls, and on triturating the dinitro compounds with conc. HClO4, nitro-nitrosyl derivatives are isolated. The solution structure and stereoretentive transformation in each step have been established from1H NMR results. The compounds are redox active and display one metal-centred oxidation and successive ligand-based reductions. The v (NO) > 1900 cm-1 strongly suggests the presence of linear Ru-N-O bonding. The electrophilic behaviour of metal-bound nitrosyl has been proved in one case by reacting with a bicyclic ketone, camphor, containing an active methylene group and an arylhydrazone with an active methine group. Diazotization of primary aromatic amines with strongly electrophilic mononitrosyl complexes in acetonotrile and dichloromethane solutions has been thoroughly studied.

The Unprecedented Reaction of Dimethylsulfonium Methylide with Michael Acceptors: Synthesis of 1‐Substituted Vinyl Silanes and Styrenes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis, Spectra and Electrochemistry of Dinitro-bis-{1-alkyl-2-(arylazo) imidazole} Ruthenium(II). Nitro-nitroso Derivatives and Reactivity of the Electrophilic {Ru-NO}6System

Ag+ assisted aquation of blue cis-trans-cis-RuCl2(RaaiR′)2 (4–6) leads to the synthesis of solvento species, blue-violet cis-trans-cis-[Ru(OH2)2(RaaiR′)2](ClO4)2 [Raai R′=p-R-C6H4 N=N–C3H2–NN–1–R′, (1–3), abbreviated as N,N′-chelator, where N(imidazole) and N(azo) represent N and N′, respectively; R = H (a), OMe (b), NO2 (c) and R′ = Me (1/4/7/10), CH2CH3 (2/5/8/11), CH2Ph (3/6/9/12)] that have been reacted with NO 2 − in warm EtOH resulting in violet dinitro complexes of the type, Ru(NO2)2(RaaiR′)2 (7–9). The nitrite complexes are useful synthons of electrophilic nitrosyls, and on triturating the compounds, (7b–9b) with conc. HClO4 nitro-nitrosyl derivatives, [Ru(NO2)(NO)(OMeaaiR′)2](ClO4)2 (10b–12b) are isolated. The solution structure and stereoretentive transformation in each step have been established from 1H n.m.r. results. All the complexes exhibit strong MLCT transitions in the visible region. They are redox active and display one metal-centred oxidation and successive ligand-based reductions. The redox potentials of Ru(III)/Ru(II) (E 1/2 M ) of (10b–12b) are anodically shifted by ~ 0.2 V as compared to those of dinitro precursors, (7b–9b). The ν(NO) >1900 cm−1 strongly suggests the presence of linear Ru–NO bonding. The electrophilic behaviour of metal bound nitrosyl has been proved in one case (12b) by reacting with a bicyclic ketone, camphor, containing an active methylene group and an arylhydrazone with an active methine group, and the heteroleptic tris chelates thus formed have been characterised.

The unprecedented reaction of dimethylsulfonium methylide with Michael acceptors: synthesis of 1-substituted vinyl silanes and styrenes

Rather than the usual cyclopropanation, conditions for an unprecedented elimination reaction from the adduct of dimethylsulfonium methylide and various Michael acceptors have been established leading to functionalized 1-substituted alkenes. In silyl substituted substrates (2a and 2h), where a facile Peterson-type olefination is possible from the adduct; elimination took place instead to give functionalized 1-substituted vinyl silanes. Aryl substituted Michael acceptors (2b-e, 2g and 2i-k) also underwent a similar kind of olefination to give 1-substituted styrene derivatives with moderate yields along with a side product, which arose by nucleophilic demethylation from the adduct of dimethylsulfonium methylide and arylidene malonates. Hammett studies revealed that selectivity for olefination vs. demethylation increases as the aryl substituent becomes more electron deficient. Alkylidene malonates (2f and 2l) with a beta-alkyl substituent did not favour the olefination process. Sequential addition of Michael acceptors and alkyl halides to a mixture of dimethylsulfonium methylide and sodium dimsylate provided olefination followed by alkylation on the active methine group. A mechanistic pathway has been formulated from the studies of a few sulfonium methylides.

Nitro–ruthenium(ii)–arylazoimidazoles: synthesis, spectra, crystal structure and electrochemistry of dinitro-bis{1-alkyl-2-(arylazo)imidazole}ruthenium(ii). Nitro–nitroso derivatives and reactivity of the electrophilic {Ru-NO}6system

Silver ion assisted aquation of blue cis,trans,cis-RuCl2(RaaiR′)2 (4–6) leads to solvento species, blue–violet cis,trans,cis-[Ru(OH2)2(RaaiR′)2](ClO4)2 [RaaiR′ = p-R–C6H4–NN–C3H2–NN-1-R′ (1–3), abbreviated as N,N′-chelator where N(imidazole) and N(azo) represent N and N′, respectively; R = H (a), Me (b), Cl (c) and R′ = Me (1/4/7/10), CH2CH3(2/5/8/11), CH2Ph (3/6/9/12)] that have been reacted with NO2− in warm ethanol resulting violet dinitro complexes of the type, Ru(NO2)2(RaaiR′)2 (7–9). The structure in one case, [Ru(NO2)2(HaaiCH2Ph)2] (9a), has been established by X-ray diffraction as the cis-Ru(NO2)2 motif along with trans-N,N and cis-N′,N′ dispositions of the chelator N atoms around the coordination sphere. The nitrite complexes are useful synthons of electrophilic nitrosyls, and on triturating the compounds 7b–9b with conc. HClO4 nitro–nitrosyl derivatives, [Ru(NO2)(NO)(MeaaiR′)2](ClO4)2 (10b–12b), are isolated. The solution structure and stereoretentive transformation in each reaction step have been established by 1H NMR results. All the complexes exhibit strong MLCT transitions in the visible region. They are redox active and display one metal-centred oxidation and successive ligand-based reductions. The redox potentials of Ru(III)/Ru(II) (E1/2M) of 10b–12b are anodically shifted by ∼0.2 V as compared to those of dinitro precursors 7b–9b. The ν(NO) > 1900 cm−1 strongly suggests the presence of linear Ru–N–O bonding. The electrophilic behaviour of metal bound nitrosyl has been proved in one case (12b) by reacting with a bicyclic ketone, camphor, containing an active methylene group and an arylhydrazone with an active methine group, and the heteroleptic tris-chelates thus formed are characterised.

ChemInform Abstract: Synthesis of 5,6‐Dihydrothieno(and furo)pyrimidines Bearing an Active Methine Group at the 4‐Position.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis of 5,6‐dihydrothieno(and furo)pyrimidines bearing an active methine group at the 4‐position

AbstractThe reactions of 2‐benzamido‐4,5‐dihydro‐3‐thiophene(and ‐3‐furan)carbonitriles (1a‐c and 4a‐c) with ethyl acetoacetate in the presence of tin(IV) chloride and triethylamine provided the corresponding ethyl 2‐(5,6‐dihydro‐2‐phenylthieno(and furo)[2,3‐d]pyrimidin‐4‐yl)‐3‐oxobutanoates (2a‐c and 9a‐c). Similarly, compounds 1a‐c and 4a‐c reacted with dialkyl malonates to give the corresponding dialkyl(5,6‐dihydro‐2‐phenylthieno(and furo)[2,3‐d]pyrimidin‐4‐yl)propanedioates (5a‐c, 6a‐c, 10a‐c and 11a‐c).

Synthesis of Dihydropyrroles and Tetrahydropyridines by the Cyclization of O-Methylsulfonyloximes Having an Active Methine Group

Synthesis of Dihydropyrroles and Tetrahydropyridines by the Cyclization of O-Methylsulfonyloximes Having an Active Methine Group

Synthesis of cyclic ethers via the palladium catalyzed intramolecular hydrocarbonation of alkoxyallenes

The intramolecular hydrocarbonation of certain alkoxyallenes ( 1, 3 and 5), bearing active methine groups at the terminus of the carbon chain, proceeded smoothly in the presence of catalytic amounts of a palladium complex [Pd(OAc) 2-dppb] to give 5- to 7-membered cyclic ethers ( 2, 4 and 6, respectively) in good to high yields.

ChemInform Abstract: Synthesis of Dihydropyrroles and Tetrahydropyridines by the Intramolecular Cyclization of O‐Methylsulfonyloximes Having an Active Methine Group.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis of Dihydropyrroles and Tetrahydropyridines by the Intramolecular Cyclization of O-Methylsulfonyloximes Having an Active Methine Group

Abstract 3,4-Dihydro-2H-pyrroles and 2,3,4,5-tetrahydropyridines are prepared from (E)-O-methylsulfonyloximes having an active methine group at γ- and δ-positions, respectively, by the treatment with DBU.

Electrochemical hydroxylation, methoxylation, and hydroxymethylation of active methine compounds

AbstractHydroxylation, methoxylation, or hydroxymethylation at the active methine group of phenylmalonate, benzylmalonate and diphenylacetate were achieved by anodic oxidation.

The base‐catalyzed transformation of polyacrylonitrile

AbstractIn an effort to produce high‐molecular‐weight, linear ladder polymer by linking the nitrile groups within the molecule of polyacrylonitrile, polyacrylonitrile homopolymers were heat treated in N,N‐dimethylformamide and N,N‐dimethylacetamide solutions, in the presence of tertiary alkylamine catalysts. The products were soluble in formic acid, had relatively low molecular weight, and could be cast into brittle films. The infrared spectra indicated that the polymerization of the nitrile groups is initiated by a self‐initiation mechanism based on the active methine groups in polyacrylonitrile, as proposed by Grassie and Hay, and that the reaction is complicated by molecular weight degradation via reverse Michael addition, as proposed by Hamada and Takahashi. The inherent viscosities of the products increase with increasing catalyst concentration, and further increases can be achieved by the addition of anionic chain coinitiators of phenolic nature. Density measurements indicated that the ladder structures undergo rearrangement into a more stereoregular form after formation, and that some aromatization occurs when the reaction is carried out in the presence of air.

Fischer indolization and its related compounds—VII : Development of abnormal fischer indolization of ortho-methoxyphenylhydrazone to provide a synthetic method for useful indole derivatives possessing an active methine group at C 6 and novel 3,6′-biindole derivatives

Fischer indolization of ethyl pyruvate 2-methoxyphenylhydrazone ( 1) with p-toluene-sulfonic acid in benzene in the presence of an enolizable dicarbonyl or an indolic compound gave either an indole product having an active methine group at C 6 or a novel type of 3,6′-biindole compound. Structures of the products were established by NMR spectra and chemical evidence.