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Showing papers on "Cyclopropane published in 1988"


Journal ArticleDOI
TL;DR: Copper complexes of chiral, C2-symmetric semicorrin ligands were found to be efficient catalysts for the cyclopropane formation from olefins with diazo compounds as discussed by the authors.
Abstract: Copper complexes of chiral, C2-symmetric semicorrin ligands were found to be efficient catalysts for the cyclopropane formation from olefins with diazo compounds. In the presence of 1 mode-% of catalyst, alkyl diazoacetates reacted smoothly with terminal olefins such as styrene, butadiene, and 1-heptene to give the corresponding optically active cyclopropanecarboxylic-acid derivatives (Table 1 Scheme 2). With one of the catalysts, enantioselectivities up to 97% ee were obtained (Table 2). Usually, the reactions were carried out using bis(semicorrinato)copper(II) complexes as precatalysts. In order to produce active catalysts, these complexes had to be activated first by heating in the presence of diazoacetate or by treatment with phenylhydrazine. Experiments with (semicorrinato)copper(I) complexes, prepared in situ from copper(I) tert-butoxide (Scheme 4), suggest that the actual catalyst is a [mono(semicorrinato)]copper(I).

249 citations


Journal ArticleDOI
TL;DR: Les calculs CAS-MCSCF et la theorie de l'etat de transition variationnel canonique sont appliques a l'isomerisation geometrique du cyclopropane.
Abstract: Les calculs CAS-MCSCF et la theorie de l'etat de transition variationnel canonique sont appliques a l'isomerisation geometrique du cyclopropane

53 citations



Journal ArticleDOI
TL;DR: In this paper, acceptor-substituted 1,3-dienes with a carbene complex occur with high regioselectivity and stereoselectivities to provide trifunctional cyclopropane derivatives.

45 citations



Journal ArticleDOI
TL;DR: In this paper, the formation mechanism of molybdenum-carbene intermediates, arising from the interaction of ethylene, propene and cyclopropane with Mo4+ ions in photoreduced silica-molyb dena catalysts for olefin metathesis, was studied by UV-Vis diffuse reflectance spectroscopy and mass spectrometry.

35 citations



Journal ArticleDOI
TL;DR: Cuprous trifluoromethanesulphonate is a highly efficient catalyst for cyclopropanation of olefins using diethyl diazomethyl phosphonate (DAMP) as discussed by the authors.

27 citations




Journal ArticleDOI
TL;DR: In this paper, the synthesis of tractable derivatives of 2-hydroxymethyl-1-amino-1 -cyclo-propanecarboxylic acid (+)- 6 and (−)- 7 in optically pure form has been achieved from the (−)-N-cyanomethyl-4-phenyl-oxozolidine synthon 2.

Journal ArticleDOI
TL;DR: In this paper, the first quinolone substrate incorporating a spiro fused cyclopropane, 8,9,10 trifluoro-2,3,4,6-tetrahydro-6-oxospiro[1H-benzo[c]quinolizine-1,l-cyclopropane]-5-carboxylic acid, ethyl ester (8), was prepared.

Journal ArticleDOI
TL;DR: In this paper, the mechanism and regioselectivity in this NO insertion into the cyclopropane ring are described, and the mixtures of two isomeric isoxazolines are obtained.
Abstract: The reaction of 1,2-diarylcyclopropanes with NOBF4 in CH3CN gave 3,5-diaryl-2-isoxazolines in good yields. For unsymmetrically substituted cyclopropanes, the mixtures of two isomeric isoxazolines were obtained. The mechanism and regioselectivity in this NO insertion into the cyclopropane ring are described.

Journal ArticleDOI
TL;DR: In the presence of trialkylstibine, dibromomalonic ester can react with electron-deficient olefins to give the title compounds in good yields.


Journal ArticleDOI
TL;DR: Aspects of cylcopropane chemistry relative to the subunit of CC-1065 are discussed in this paper, where the authors also discuss the relationship between cylcoprocessor chemistry and subunit decomposition.

Journal ArticleDOI
TL;DR: The reactions between atomic nickel and cyclopropane in cryogenic matrices have been investigated in this article, where the reaction was shown to form a four-membered unligated metallacycle, nickelacyclobutane, with visible photolysis induced metathesis through Ni-C and C-C bond cleavages.

Journal ArticleDOI
TL;DR: In this paper, the reaction of C 5 H 5 (CO) 2 Fe(CH 2 ) 3 Br with AgBF 4 in benzene leads to formation of cyclopropane in 73% yield.

Journal ArticleDOI
TL;DR: Cyclopropene (4, X = Ph) reacts with 2, 3-dirnethylbut-2-ene or methyl methacrylate to produce predominantly the cyclopropanes (5k) and (5m) with an E-stereochemistry at the alkene and, in the latter case, the cis stereochemistry of the ester about the cyclopsane as discussed by the authors.


Journal ArticleDOI
TL;DR: In this paper, rate constants have been obtained for CH(X 2Pi) radical reactions with cyclopropane, cyclopentane, and cyclohexane in order to establish the rate of CH insertion into secondary C-H bonds in alkanes.
Abstract: Rate constants have been obtained for CH(X 2Pi) radical reactions with cyclopropane, cyclopentane, and cyclohexane in order to establish the rate of CH insertion into secondary C-H bonds in alkanes. Data indicate that there is no measurable dependence on photolysis laser energy. The reactions all exhibited rate constants that decrease with increasing temperature. It is suggested that a possible set of pathways for the cycloalkane reactions is a ring-opening process where the excited adduct decomposes to a hydrogen atom and a diene.

Journal ArticleDOI
TL;DR: In this article, five new captodative substituted cyclopropanes have been synthesized and their structures determined from X-ray diffraction data, including cis-1,2-dicyano-1-2-dimethyl-(1), trans-1.2-Dicapto-substitution, cis- 1-D-cyclopropane (C2D-CyclopropANE), trans 1.2D cyclopane (T2Dcyclopane), trans 2-CycleCyclecyclopANE (T
Abstract: Five new captodative (cd) substituted cyclopropanes have been synthesized and their structures determined from X-ray diffraction data. These are cis-1,2-dicyano-1,2-dimethyl-(1), trans-1,2-dicyano-1,2-bisethoxycarbonyl-(2), cis-1,2-dicyano-1,2-dimethoxy-(3), trans-1,2-dicyano-1,2-bismethylthio-(4), and trans-1,2-dicyano-1,2-bis(dimethylamino)-cyclopropane (5). These structures have been solved by direct methods and refined by least-squares using 865, 1 332, 766, 1 075, and 1 341 reflections respectively, to R 0.062, 0.041, 0.044, 0.031, and 0.049. This work completes former results and permits the discussion of the influence of polar substituents on cyclopropane geometry in relation to their reported ease of cis–trans isomerization. The effect on ring bond lengths is small but significant: in both captodative and dicapto-substitution, the distal ring bond is shortened and vicinal bonds are lengthened. Mean distal-bond shortenings are proposed for SR, OR, and NR2; the values calculated for C=N, C=O, and phenyl agree with published data. The particular facile isomerization of cd cyclopropanes appears best explained, not as the consequence of a destabilized ground state but rather as increased spin delocalization in the transition state.

Journal ArticleDOI
TL;DR: The Raman and far-infrared spectra of 1,1-dicyanocyclopropane have been recorded and the vibrational assignments for these two molecules have been revised as mentioned in this paper.
Abstract: The Raman (3500–10 cm−1) and far-infrared (400–70 cm−1) spectra of solid 1,1-dicyanocyclopropane have been recorded. The molecular structure of cyclopropane, cyanocyclopropane and 1,1-dicyanocyclopropane have been calculated by ab initio methods at the 4-31G basis set level. The harmonic force fields for cyanocyclopropane and 1,1-dicyanocyclopropane have also been calculated using the same basis set. By the combination of experimental data and normal coordinate calculations with scaled ab initio force constants, the vibrational assignments for these two molecules have been revised. Discrepancies between the previously reported and present assignments are discussed. The molecular structures of cyanocyclopropane and 1,1-dicyanocyclopropane obtained in this work are compared with the molecular structure of cyclopropane.

Journal ArticleDOI
TL;DR: In this paper, a ring expansion was proposed by way of a protonated cyclopropane to obtain 5-ketocamphene, tricyclenone and endo-2,4-dimethylbicyclo.

Journal ArticleDOI
TL;DR: In this paper, the experimental results confirm that the molecular configuration with the carbonyl group cis to the planes of the two rings is the predominant species in the liquid state, though evidence for a second conformer which is tentatively identified as the cis-trans conformer, is presented.


Journal ArticleDOI
TL;DR: Raney nickel converted both of these thio sugar derivatives into the same product, namely, 1-acetamido-1,2-dideoxy-3,4:5,6-di-O-isopropylidene-2-C-methyl-D-mannito l, for the design of stereospecific syntheses of chiral isoalkyl structures is proposed.

Journal ArticleDOI
TL;DR: In this article, a Dicyanoanthracene-sensitized photoreaction of electron-rich 1,2-diarylcyclopropanes with NO in acetonitrile has been described.
Abstract: 9,10-Dicyanoanthracene-sensitized photoreaction of electron-rich 1,2-diarylcyclopropanes with NO in acetonitrile afforded 3,5-diaryl-2-isoxazolines in good yields. The cyclopropanes bearing different aryl-substituents gave a mixture of two isomeric 2-isoxazolines. Mechanistic features of this reaction are described.

Journal ArticleDOI
TL;DR: In this article, the conversion of a series of 2,3-dimethylated 1-aminocyclopropanecarboxylates by apple tissues into mixtures of cis- and trans-butenes is reported; the results are in accord with a stepwise enzymatic mechanism of cyclopropane ring opening.
Abstract: The conversion of a series of 2,3-dimethylated 1-aminocyclopropanecarboxylates by apple tissues into mixtures of cis- and trans-butenes is reported; the results are in accord with a stepwise enzymatic mechanism of cyclopropane ring opening.

Journal ArticleDOI
TL;DR: In this article, the ligand effect on catalyst reactivity and selectivity when changing the complex central metal ion [cmi, M(III)] from Al to Cr to Fe was investigated.