Aminonitrile rearrangement and the cleavage of 1,1-dialkyl-δ2-tetrahydropyridazinium salts

1,1-Dimethyl- and 1-ethyl-1-methyl-²-tetrahydropyridazinium iodides undergo an aminonitrile rearrangement under the action of alkali with the formation of-dialkylaminobutyronitriles.The aminonitrile rearrangement has been used as a method of showing the structure of the oxidation product of 3-methylhexahydropyridazine which is 6-methyl-²-tetrahydropyridazine.Under the action ot NaOH, 3-methyl-substituted ²-tetrahydropyridazinium salts, for which the aminonitrile rearrangement is excluded split off the substituent from the nitrogen atom and undergo far-reaching decomposition.     

Investigations in the benzazole and naphthazole series

The methylation of 1-benzazolyl-3, 5-diphenylformazans (I–III) with methyl iodide takes place at the nitrogen atom of the heterocycle and the methyl derivatives obtained do not undergo oxidation to free radicals-verdazyls. On methylation with diazomethane, 1-(benzimidazol-1-yl)-3, 5-diphenylformazan (I) and 1-benzoxazolyl-3,5-diphenylformazan (III) form analogous methyl derivatives. In contrast to this, on methylation with diazomethane 1-benzothiazolyl-3, 5-diphenylformazan (II) is converted into a methyl derivative which, in benzene solution, undergoes spontaneous oxidation to 1-benzothiazolyl-3, 5-diphenylverdazyl (VII).For part XXIV, see [1].     

Synthesis of Azaphenanthrene Derivatives by Condensation of 2-Methyleneaminonaphthalene with Cyclic β-Diketones

2-Methyleneaminonaphthalene smoothly reacts with cyclic -diketones to afford azaphenanthrene derivatives in high yield. The dihydropyridine ring in the products can be oxidized to pyridine ring. The oxidation products, unlike their precursors and analogs having an aryl substituent in the -position with respect to the nitrogen atom, react with hydroxylamine at the carbonyl group to give the corresponding oximes and in some cases undergo Knoevenagel condensation with malononitrile. Hydrolysis of the condensation product yields the respective diamide.     

N-Substituted <Emphasis Type="Italic">N</Emphasis>-Phosphinotrifluoroactetamides in the Staudinger Reaction

Formerly unknown phosphazides with N-trifluoroacetamido groups at the phosphorus atom were obtained by the imination of N-(diphenylphosphino)-N-phenyltrifluoroacetamide with aryl azides. Stability of the phosphazides was found to depend on the nature of the radical at the amide nitrogen atom. The phosphazides were shown to readily eliminate nitrogen to yield phosphinimines that undergo the aza-Wittig thermal rearrangement into N-phosphorylated trifluoroacetamidines.     

Nitrogen-doped zirconia: A comparison with cation stabilized zirconia

The conductivity behavior of nitrogen-doped zirconia is compared with that of zirconia doped with lower-valent cations and discussed in the framework of defect-defect interactions. While nominally introducing the same number of vacancies as yttrium, nitrogen dopants introduced in the anion sublattice of zirconia lead to substantially different defect kinetics and energetics. Compared to the equivalent yttrium doping nitrogen doping in the Y-Zr-O-N system substantially increases the activation energy and correspondingly decreases the conductivity at temperatures below in the vacancy range below 4 mol%. The comparison of N-doped zirconia and zirconia systems doped with size-matched cation stabilizers, such as Sc, Yb and Y, shows that elastically driven vacancy-vacancy ordering interactions can phenomenologically account for the temperature- and composition-dependence. It is striking that materials with superior high-temperature conductivities due to weak dopant-vacancy interactions undergo severe deterioration at low temperature due to the strong vacancy-ordering. The analysis also explains qualitatively similar effects of Y co-doping in Yb-, Sc-, and N-doped zirconia. Small amount of Y in N-doped zirconia as well as in Sc-doped zirconia appears to hinder the formation of the long-range ordered phase and thus enhance the conductivity substantially.     

Research on 1, 2, 4-triazoles

The stability of sulfides and sulfones of 1-aryltetrazoles and 4-aryl-1, 2, 4-triazoles depends on the acceptor character of the heterocyclic ring. Unlike tetrazole sulfides, triazole sulfides do not undergo hydrolysis, Tetrazole sulfones are more readily hydrolyzed than triazole ones. When an electron-donor substituent is introduced into the p-position of the phenyl ring, the rate of hydrolysis is cut. Neither triazole nor tetrazole sulfides and sulfones, not arylated at a nitrogen atom, are hydrolyzed by alkali, because of a partial decrease in positive charge at the carbon atom of the sulfoazomethine group through formation of an anion with a sextet of -electrons in the ring. Hydrolysis of sulfides and sulfones can conveniently be used to prepared 1-aryltetrazolinones-5 and 4-aryl-1, 2, 4-triazolinones-3.For Part V see [8].     

Investigation of lactams

From an examination of the PMR spectra, polarographic data, and molecular models of-enamines of capro- and valerolactams, it is concluded that there is a different degree of conjugation of the p electrons of the piperidine nitrogen with the enamine double bond and that this explains the differences in the tendency of these compounds to undergo hydrolysis.See [1] for communication XXI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 530–532, April, 1974.     

One-electron oxidation of 1,3,5-triaryl-2-pyrazolines by antimony pentachloride

Upon reaction of 1,3,5-triphenyl- and 1,3,5-triphenyl-5-methyl-2-pyrazolines with antimony pentachloride in acetonitrile they undergo oxidation to cation radicals, which subsequently undergo rapid dimerization at the para positions of the N-phenyl groups. The final products are 4,4-bis(3,5-diphenyl-2-pyrazolin-1-ia)- and 4,4-bis(3,5-diphenyl-5-methyl-2-pyrazolin-1-ia)bis(cyclohexa-2,5-dienylidene) hexachloroantimonates.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 551–554, April, 1985.     

Reaction of 2-alkoxycarbonylmethyl derivatives of δ2-oxazoline and δ2-imidazoline and their tautomers with 4-nitrobenzonitrile N-oxide

It was established that 2-alkoxycarbonylntethylene derivatives of oxazolidine and imidazolidine react readily with 4-nitrobenzonitrile N-oxide; the reaction takes place at the methylidyne carbon atom to give intermediate oximes, which can then undergo cyclization to isoxazoles. Their tautomers —benzimidazole and ² -oxazoline derivatives —react with considerably greater difficulty; in the first case the reaction takes place at a different center, viz., the ring nitrogen atom.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 681–684, May, 1991.     

NO Release from trans-[Ru(NH3)4L(NO)]3+ Complexes Upon Reduction (L = 1-Methylimidazole or Benzoimidazole)

The synthesis, characterization and reactivity of trans-[Ru(NH₃)₄(L)NO](PF₆)₃(L = benzoimidazole or 1-methylimidazole in trans position to NO) are presented. ¹H-n.m.r. spectroscopy data indicate that the benzoimidazole and 1-methylimidazole ligands are coordinated to Ru^II through carbon and nitrogen, respectively. The nitrosyl stretching frequencies [(NO) > 1900 cm^–1] suggest that the coordinated nitrosyl has substantial NO⁺ character. The complexes undergo a single-electron reduction (E ⁰–0.245 versus NHE), which involves the coordinated nitrosyl. Dissociation of NO in the reduced species is facilitated by the 1-methylimidazole ligand, which is not observed for the benzoimidazole species. The complex with 1-methylimidazole does not suffer hydroxide attack on the NO⁺, at least at pH values lower than 11.     

Benzenoid-quinoid tautomerism of azomethines and their structural analogs. 41. Photo- and thermochromic transformations of acylated N-alkylimines of 3-hydroxybenzo[b]thiophene-2-carbaldehyde and 3-hydroxy-1-methylindole-2-carbaldehyde

O- and N-Acylated alkylimines of 3-hydroxybenzo[b]thiophene-2-carbaldehyde and 3-hydroxy-1-methylindole-2-carbaldehyde were synthesized. Their Z E isomerizations and NO-acyl photo- and thermotransformations were investigated by means of electronic and IR spectroscopy. On irradiation N-acyl-N-methyl(or benzyl)amino-methylene derivatives of benzo[b]thiophen-3-one and 1-methylindol-3-one undergo only Z E isomerization. The introduction of bulkier alkyl substituants (isopropyl, cyclohexyl) relative to the amino nitrogen atom increases the stability of the O-acyl isomers and their conjugate acids and leads to irreversible photoinitiated or acid-catalyzed N O-acyl rearrangements. Exclusively the O-acyl isomer is realized for compounds with the most bulky N-tert-butyl substituent.See [1] for Communication 40.Translated from Khimika Geterotsiklicheskikh Soedinenii, No. 4, pp. 466–471, April, 1988.     

Synthesis of dialkyl, diaryl and metallacyclic complexes of Ni and Pd containing pyridine, α-diimines and other nitrogen ligands: Crystal structures of the complexes cis-NiR2py2 (R=benzyl, mesityl)

The alkylation of NiCl₂py₄ or PdCl₂py₂ with organomagnesium or organolithium reagents affords dialkyl complexes cis-MR₂py₂ (R=Me, CH₂SiMe₃, CH₂Ph, CH₂CMe₂Ph, 2,4,6-C₆H₂Me₃). The methyl and trimethylsilyl derivatives undergo ligand exchange reactions with chelating nitrogen ligands (α-diimines or 2-imidoylpyridines), yielding the corresponding dialkyl derivatives in good to excellent yields. A catalytic amount of PMe₃ induces the transformation of the nickel complex Ni(CH₂CMe₂Ph)₂py₂ into the metallacyclic derivative .The latter, and the related palladacycle , also undergo facile ligand exchange reactions.     

Untersuchungen im System Nb—Mo—N

The system Nb–Mo–N has been investigated by X-ray techniques in an isothermal section at 1100C and at nitrogen pressures ranging from 1 to 300 bar. In the binary phase-Mo₂N up to 23% of the Mo-atoms can be replaced by Nb-atoms at a nitrogen pressure of 300 bar, while only a small amount of molybdenum nitride is soluble in the binary nitrides of niobium even under high nitrogen pressures. The composition range of the ternary phase NbMoN has been investigated with respect to nitrogen content as well as metal composition. The possibility of substitution of Mo-atoms by W-atoms within theZ-phase has been checked.

     

Cyclometallation,part II. I.r. and1H N.m.r. studies of palladium(II) compounds with substitutedN-(benzylidene)amines

Summary New cyclometallated complexes of palladium containing substitutedN-(benzylidene)amines have been prepared and characterized. Palladium(II) acetate is used to make the acetato-bridged dimers, which undergo metathetical reactions to give the halo-bridged dimers. These when treated with PPh₃ or P(C₆H₁₁)₃ in a 12 molar ratio yield the phosphine monomers. I.r. and¹H n.m.r. studies show that palladium is coordinated through nitrogen, and also reveal the disposition of the halogen and phosphine ligands in the monomeric complexes.     

3-Hydroxyphenyl derivatives of pyrazolines and tetrahydropyridazines in a catalytic decomposition reaction

The isomeric 3-(hydroxyphenyl)-1,4,5,6-tetrahydropyridazines differ from their five-membered-ring analogs, the 3-(hydroxyphenyl)-²-pyrazolines, in their behavior in catalytic-decomposition reactions. The catalytic conversion of 3- (hydroxyphenyl)-1,4,5,6-tetrahydropyridazines takes place at 120–200° C, dehydrogenation being the main reaction. The hydroxyphenylpyrazolines, under the same conditions, undergo decomposition with liberation of nitrogen and formation of the corresponding cyclopropanes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 5, pp. 657–659, May, 1970.     

Thermo-driven chiroptical switching polysilane featuring 2-cyclopentylethyl side group

A new rod-like helical polysilane, poly{(S)-3,7-dimethyloctyl-(2-cyclopentylethyl)silane}, was found to undergo a thermo-driven, helix-helix transition at –33 ° C in isooctane associated with the discontinuous changes in the Si -Si *transition energy and intensity in the transition temperature region. This is the first example of a helix-helix transition polysilane with a cycloalkyl group. A similar rod-like polysilane derivative, poly{(S)-3,7-dimethyloctyl-(1-cyclopentylmethyl)silane}, however, did not undergo any helix-helix transition between –61 and 80 ° C.     

Diastereo- and regioselective Diels-Alder reactions of 2-phosphaindolizines

1,3-Bis(alkoxycarbonyl)-2-phosphaindolizines undergo Diels-Alder reactions at the CP- functionality with 2,3-dimethylbutadiene and with isoprene in the presence of sulfur with complete diastereoselectivity. The reaction with isoprene occurs with 100% regioselectivity as well. 3-Ethoxycarbonyl-1-methyl-2-phosphaindolizine, however, fails to undergo Diels-Alder reaction under these conditions. Difference in the dienophilic reactivities of mono- and bis(alkoxycarbonyl) substituted 2-phosphaindolizines and the observed regioselectivity in the Diels-Alder reaction has been rationalized on the basis of DFT calculations. The relative stabilities of the transition structures have been explained on the basis of the NBO analysis.     

Synthesis of 1,3-thiazoline derivatives from β-dicarbonyl compounds and phenacyl thiocyanate

Acetylacetone and ethyl acetoacetate undergo addition at the CN bond of phenacyl thiocyanate in the presence of Ni(acac)₂ to give the respective keteneN, S-acetals, which undergo smooth cyclization to afford 2-methylene-4-phenyl-1, 3-thiazoline derivatives when refluxed in THF.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1938–1940, November, 1993     

Application of experimental (FT-ICR) and theoretical (AM1) methods to the study of proton-transfer reactions for tautomerizing amidines in the gas phase

Semiempirical calculations (AM1) together with experimental mass spectrometric (FT-ICR) data indicate the imino nitrogen atom as the favoured site of protonation and the amino nitrogen atom as the site of deprotonation of the amidine group in the gas phase. For tautomerizing N-methyl-N-phenylbenzamidine the tautomer with the phenyl group at the imino nitrogen atom weakly predominates in tautomeric mixture.