Norcaradiene-cycloheptatriene substituted in position 7: Investigation of the valence isomerization equilibrium

Summary The valence isomerism of a series of noncaradiene-cycloheptatriene compounds is investigated. Geometry and energy calculations allow to explain the nature of the transitions. Peculiarities of equilibrium shifts between different structures depending on the substituent at position 7 (X=CH₃, NH₂, CHO, CN) are discussed. Th nature of the interaction between the substituentX and the ring (- or -interaction) is investigated.

---

Norcaradiene-Cycloheptatrien mit Substituenten in Position 7: Untersuchungen der Valenzisomeriegleichgewichte (Kurze Mitt.)

Zusammenfassung Es wurden Gleichgewichte zwischen Norcaradien und Cycloheptatrien mit Hilfe der semiempirischen Methoden MNDO und AM1 untersucht. Die Elektronendichteverteilungen und H _f-Werte der untersuchten Verbindungen werden in Abhängigkeit der Substituenten diskutiert.

     

Reaction of enol ethers with zinc carbenoid reagents. Cyclopropanation and subsequent isomerization to allylic ethers

The reactions of enol ethers (ROCC, R = alkyl, silyl) with zinc carbenoid reagents were found to give allylic ethers in several cases along with the expected cyclopropyl ethers. The ratio of these two products was highly dependent on the concentration of the reaction mixture. Thus, the selective formation of each product was conveniently attained by merely changing the amounts of the solvent used. Zinc iodide, a by-product of the reaction, plays a key role in the present cyclopropyl to allylic rearrangement. Ring-opened ionic intermediates are proposed.     

Reaction of substituted 7-cyclopropyl-1,4-benzodioxanes with dinitrogen tetraoxide

The reaction of 6-bromo-7-cyclopropyl-1,4-benzodioxane with N₂O₄ in methylene chloride does not affect the cyclopropane ring and forms the nitrodebrominated product (ipso-substitution). The same reaction of 6-nitro- and 5,6-dinitro-7-cyclopropyl-1,4-benzodioxanes produces only the products with an modified threemembered ring. The difference in the reaction paths of the studied cyclopropylbenzodioxanes with N₂O₄ is explained by the different ratio of substrate to one-electron oxidant, the nitrosyl cation.M. V. Lomonosov Moscow State University, Moscow 119899Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 324–329, March, 1999.     

New iron complexes from nucleophile addition/carbonylation of η4-(1,3-diene)tricarbonyliron(0) complexes

A series of novel organoiron complexes has been isolated and studied by ¹H NMR, ¹³C NMR, and IR spectroscopy. Addition of LiC(CH₃)₂CN to (1,3-cyclohexadiene)tricarbonyliron produces an intermediate which is only stable at low temperature and which is assigned the homoallyl—Fe(CO)₃ anion structure. The intermediate rearranges on warming into a stable complex, for which full spectral data support the structure as an allyl—Fe(CO)₃ anionic species. Interception of the first formed intermediate with CO gives an acylferrate complex with an olefin unit still bound to iron, and methylation then occurs at oxygen to produce an unusual internally-bound (alkene)(methoxyalkylidene)tricarbonyliron species.     

Synthesis and characterization of substituted aminobiphenylglyoximes and their complexes with some transition metals

In this study, four different new vic-dioximates, [L¹H₂] N-(4-ethylphenyl)amino-biphenylglyoxime, [L²H₂] N-(4-butylphenyl)aminobiphenylglyoxime, [L³H₂] N-(4-aminoacetanilide)aminobiphenylglyoxime, and [L⁴H₂] N-(thiazol-2-yl-aminobiphenylglyoxime are synthesized from anti-4′-biphenylchloroglyoxime and the corresponding substituted aromatic amines. The Co(II), Ni(II), and Cu(II) complexes of these ligands are prepared. The structures of these new ligands and their complexes are proposed based upon IR, ¹H, and ¹³C NMR spectral data, mass spectroscopy, magnetic susceptibility measurement, and elemental analyses. The text was submitted by the authors in English.     

Reaction of nitrosonium trifluoromethanesulfonate with fluoroolefins and some properties of the resulting products

The reaction of nitrosonium trifluoromethanesulfonate with fluoroolefins resulted in -nitrosofluoroalkyltrifluoromethanesulfonates, the corresponding 1,2-oxazetidines, and nitrosofluoro polymers. The nitroso compounds, under the effect of nitrogen tetroxide, were oxidized to -nitrofluoroalkyltrifluoromethanesulfonates. Pyrolysis of the oxazetidines and nitrosofluoro polymers resulted in the synthesis of fluoroazomethines containing the CF₃-SO₂O group.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1851–1855, August, 1990.     

Enantioselective synthesis of substituted pyrans via amine-catalyzed Michael addition and subsequent enolization/cyclisation

An organocatalytic construction of optically enriched substituted pyran derivatives via amine-catalyzed Michael addition and subsequent enolization/cyclisation has been described starting from electronically poor alkenes. Functionalized pyrans were obtained in high enantioselectivities (up to 96%) and good yields (up to 90%) having three contiguous chiral centers.     

Electron impact-induced decomposition of some substituted 7-ethoxycarbonylpyridopyrrolidenequinolines

The electron impact ionization mass spectrometric behaviour of three cycloadducts of 4,6-benzo[h]naphthyridinum ethoxycarbonylmethylide with acrylonitrile, ethyl acrylate and diethyl maleate was studied with the aid of exact mass measurements and metastable transitions. The study showed that the electron impact-induced decomposition of substituted pyridopyrrolidenequinolines occurs exclusively on the aliphatic five-membered ring.     

用NMR法研究几种不对称双烃基硫桥六羰基二铁的异构化动力学

本文用常规核磁共振方法研究了(苄基硫)(烃基硫)六羰基二铁(烃基为甲基、乙基)和动态核磁共振方法研究了(苄基硫)(叔丁基硫)六羰基二铁的异构化反应动力学, 提出了可能的反应机理, 讨论了影响反应速率的因素.     

Reaction of aminoquinolines with methyl acrylate and transformations of some of the products obtained

3H,4H-Quino[1,2-a]-2-pyrimidone, 1-(2-carboxyethyl)aminoquinolinium betaines, and methyl esters of N-quinolinyl--alanines were isolated from the reactions of aminoquinolines with methyl acrylate. Hydrolysis of the latter yielded the corresponding amino acids, two of which were converted to 1-(3- and 6-quinolinyl)dihydrouracils, and the latter was reduced to 1-(6-quinolinyl)-2-oxohexahydropyrimidine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 482–486, April, 1971.     

Oxidative addition of allylic carbonates to palladium(0) complexes: reversibility and isomerization

The oxidative addition of a cyclic allylic carbonate to the palladium(0) complex generated from a [Pd(dba)2]+2 PPh3 mixture affords a cationic pi-allylpalladium(II) complex with the alkyl carbonate as the counter-anion. This reaction is reversible and proceeds with isomerization of the allylic carbonate at the allylic position. The equilibrium constant has been determined in DMF. The influence of the precursor of the palladium(0) is discussed.     

Synthesis and polarographic studies of some phenylazo substituted tetra-aza macrocycle complexes

The preparation of some phenylazo substituted tetra-aza macrocycle complexes is reported. The electrochemical properties of these compounds have been examined using polarographic and voltammetric techniques. These studies revealed that both the ligand and metal are electrochemically active. The reduction of the azo function has been shown to occur through a single four-electron process. When a nitro group was also present the nitro function was reduced in a six-electron wave, cathodic of the azo moiety.     

A spectroscopic study of some substituted tris(diimine) complexes of ruthenium(II) and their reduction products

The electronic absorption and resonance Raman spectra of the parent and one- to six-electron reduction products of tris(5,5′-bis(ethoxycarbonyl)-2,2′-bipyridine)ruthenium(II) and tris(5,5′-bis(phenyl)- 2,2′-bipyridine)ruthenium(II) indicate that the redox orbitals are single-ring localized throughout the reduction series. The analogous 4,4′-complexes exhibit extensive shifts of both electronic absorption bands and vibrational bands as electrons are added. The shifts are rationalized within the localized redox orbital model. The occurrence of backbonding between the metal and unreduced ligands can successfully account for the observed shifts in the vibrational spectra, while electrostatic interaction between redox orbitals is consistent with the observed shifts in the electronic spectra.     

Product distributions in the addition of the hydride ion to cyclopentadienyliron complexes of substituted benzenes

Fifteen [C₆H₅(X)FeCp]⁺ cations with substituents X having different electron-donating or electron-withdrawing effects were treated with NaBH₄ in glyme or THF. The relative distributions of products from o-, m-, p- and ipso-additions of the hydride ion to the arene ring were determined by high resolution ¹H NMR. For the η⁶-N,N-dimethylaniline-η⁵-cyclopentadienyliron cation with the most electron-donating of the substituents studied, only m- and p-hydride addition products were obtained, while in the reaction with the η⁶-nitrobenzene-η⁵-cyclopentadienyliron cation, which contained the most electron-withdrawing of the substituents investigated, only the o-addition product was formed. For the other 13 cations, with X  C₆H₅O, CH₃O, p-CH₃C₆H₄S, C₆H₅CH₂, (CH₃)₃C, CH₃, CH₃CH₂, C₆H₅, Cl, COOCH₃, C₆H₅CO, CN and p-CH₃C₆H₄SO₂, o-, m- and p-hydride addition products were obtained in all cases, with a few instances also giving very minor amounts of ipso-adducts. The relative product distributions observed were interpreted by suggesting that while electronic effects played a major role, steric factors and free valency effects favoring o-addition as suggested by MO calculations [5] could also exert their influence in giving rise to the overall results.