Cycloadditions of diazoesters to α,β-unsaturated aldehydes

Noels, Alfred F.; Braham, J. N.; Hubert, Aurélia; Teyssié, Ph.

doi:10.1016/0040-4020(78)80237-3

Cited by 16 publications

(5 citation statements)

References 11 publications

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“…The IR spectra contain absorption bands for the CO, CO 2 , and OH substituent in these compounds and also by a set of signals characteristic of their heterocycles [13] (see Experimental section). The 1 H NMR spectra of pyrazolines 2, 3 agree with those of known 4,5-dihydro-1H-pyrazoles [14][15][16]. They show two signals for the H-4 ring protons each as double doublets and a similar form for the H-5 proton signal at lower field.…”

Section: -Carboxylate Obtainedsupporting

confidence: 66%

Synthesis and reactions of methyl 3-(1-adamantyl-carbonyl)-4,5-dihydro-1H-pyrazole-5-carboxylate

Lozhkin

Петров

Докичев

et al. 2009

Chem Heterocycl Comp

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The development of methods for preparing novel adamantane derivatives is a current problem since representatives of this class of compound have a broad spectrum of physiological activity (psychostimulating, immunostimulating, anticancer, analgesic) and are used in medical practice as antiviral, anti-parkinsonian, and other preparations [1][2][3][4]. It is known that adamantyl-substituted pyrazole shows high antibacterial activity and is of interest as a chemotherapeutic agent [2].The 1,3-dipolar cycloaddition of diazo derivatives to unsaturated compounds [5,6] shows promise in the synthesis of five membered nitrogen heterocycles and this opens up broad possibilities for preparing novel, practically important polyfunctional materials of different structure. This methodology was used by us in the case of the synthesis of 3-aminopyrrolidin-2-ones, dihydrooxazolines, and 1,3-propylenediamines of the norbornane series [7][8][9][10].With the aim of preparing compounds containing a nitrogen heterocycle and an adamantane fragment we have, for the first time, in this work studied the 1,3-dipolar cycloaddition of 1-(1-adamantyl)-2-diazoethanone (1) to methyl acrylate. On the basis of the methyl 3-(1-adamantylcarbonyl)-4,5-dihydro-1H-pyrazole-

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Section: -Carboxylate Obtainedsupporting

confidence: 66%

Synthesis and reactions of methyl 3-(1-adamantyl-carbonyl)-4,5-dihydro-1H-pyrazole-5-carboxylate

Lozhkin

Петров

Докичев

et al. 2009

Chem Heterocycl Comp

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“…[30] The reaction is spontaneous at very high concentrations and alternatively can be catalyzed by Lewis acids and bases as well as by Brønsted acids initially to provide 4,5dihydro-3H-pyrazoles as unstable intermediate species that tautomerize to the corresponding 4,5-dihydro-1H-pyrazole isomers. [31][32][33] The stability of such products is highly dependent on the alkene used. It is known that decomposition can be spontaneous or promoted by acids or bases [34] with dinitrogen loss, and this leads to the corresponding cyclopropyl derivatives (Scheme 2).…”

Section: Resultsmentioning

confidence: 99%

Supramolecular Encapsulation of Neutral Diazoacetate Esters and Catalyzed 1,3‐Dipolar Cycloaddition Reaction by a Self‐Assembled Hexameric Capsule

et al. 2014

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Diazoacetate esters proved to be suitable neutral guests for\ud the self-assembled resorcin[4]arene hexameric capsule. The hydrogen- bonded supramolecular host catalyzed the 1,3-dipolar cycloaddition reaction between diazoacetate esters and electron- poor alkenes such as acrolein, acrylonitrile, crotonaldehyde, trans-2-hexenal, methyl, and butyl acrylate,\ud which led to the corresponding 4,5-dihydro-1H-pyrazole\ud derivatives. The cycloaddition reaction occurred within the\ud cavity of the capsule. In fact, substantial inhibition of the catalytic activity was observed by employing tetraethylammonium tetrafluoroborate characterized by greater affinity for the hexameric capsule as a competitive guest; its presence inhibited access of the substrates. The 1,3-dipolar cycloaddition reaction between diazoacetate esters and acrylate esters of different lengths showed a significant degree of substrate selectivity owing to the encapsulation of the reagents before the cycloaddition reaction

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“…«» f (Sr)*dm 0 where all quantities have their usual meanings. It is this approximation that has mostly been used to study the linear stability of massive objects (Ledoux, 1941;Schwarzschild and Härm, 1959;Stothers and Simon;1970;Papaloizou, 1973;Noels and Masereel, 1982;and Maeder, 1985;see, however, Ziebarth, 1970). For the stability analysis we constructed a sequence of models from 130 Μ Θ to 5000 M 0 with a chemical composition of {X,Z) = (0.687,0.043).…”

Section: The Imaginary Part Of the Eigenfrequency In Ledoux's (1941) mentioning

confidence: 99%

The critical mass for the overstability of massive zero-age main sequence stars

Klapp

Langer

Fricke

1988

Symp. - Int. Astron. Union

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The linear stability of massive extreme Pop I stars at the main sequence is investigated with a full nonadiabatic treatment. Contrary to earlier beliefs these stars become vibrationally unstable only beyond a critical mass as high as 440 M© at the main sequence. It has been maintained now for a very long time since the classical work by Ledoux (1941) and by Schwarzschild and Härm (1959) that stars in excess of ~ 100 M© cannot exist on the ground of their overstability alone. According to these results the nuclear energizing of pulsations in the stellar core -the e-mechanism -overcomes the damping and is believed to essentially disrupt the star or to cause strong mass loss which reduces their lifetimes effectively. On the other hand, evidence for the existence of stars with masses well in excess of 100 M 0 has come from observations of the brightest stars in the galaxies of the Local Group (Humphreys, 1982; De Jager, 1980; Massey and Hutchings, 1983) and from the interpretation of Wolf-Rayet stars (Maeder, 1982), Ρ Cygni stars and Hubble-Sandage variables, etc. (Humphreys, 1984). The extreme phenomena like η Carina in our galaxy and R136a in the LMC call for main sequence masses in excess of hundred solar masses. Langer et al., 1985). We have taken special care in using identical input physics both in stellar evolution code and in the pulsation code. Motivated by the apparent discrepancy between theory and observations concerning the upper mass limit, we reconsider in this paper the linear theory for radial pulsations of massive stars. The linear stability analysis is performed with a modified version of the Los Alamos Nonadiabatic Code (LNA). The major modifications introduced to the LNA code are (i) construction of the equilibrium model and (ii) inclusion of a nuclear energy generation term into the energy equation. For our computations the equilibrium model is constructed with the Göttingen stellar evolution code (cf.In the LNA code a first guess to the eigenfrequency is obtained by the use of the quasiadiabatic approximation and a first order expansion about the adiabatic mode. From Dalsgaard and S. Frandsen (eds.), Advances in Helio-and Asteroseismology, 399-402. © 1988 by the I AU. 399 J. Christensen-

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Cycloadditions of diazoesters to α,β-unsaturated aldehydes

Cited by 16 publications

References 11 publications

Synthesis and reactions of methyl 3-(1-adamantyl-carbonyl)-4,5-dihydro-1H-pyrazole-5-carboxylate

Synthesis and reactions of methyl 3-(1-adamantyl-carbonyl)-4,5-dihydro-1H-pyrazole-5-carboxylate

Supramolecular Encapsulation of Neutral Diazoacetate Esters and Catalyzed 1,3‐Dipolar Cycloaddition Reaction by a Self‐Assembled Hexameric Capsule

The critical mass for the overstability of massive zero-age main sequence stars

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