Eine verbesserte Synthese von Chinuclidin‐4‐carbonsäure. Chinuclidinreihe, 10. Mitteilung

Eckhardt, W.; Grob, C. A.; Treffert, W. D.

doi:10.1002/hlca.19720550719

Cited by 15 publications

(4 citation statements)

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“…4-Carboxyl-1 -methylquinuclidinium(3-y)perchlorate. 1.83 g (10 mmol) 4-ethoxycarbonyl-quinuclidine [20] were converted to the methiodide with 1.70 g (12 mmol) methyl iodide in 5 ml acetone. The salt was precipitated with ether.…”

Section: Cfjh14cin06 (231636)mentioning

confidence: 99%

The Transmission of Polar Effects Polar Effects. Part II

Grob

Kaiser

Schweizer

1977

Helvetica Chimica Acta

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SummaryThe pK: values for nine acyclic, mono-and bicyclic a-, p-and y-(trimethy1)ammonio acids, 1 (a-y), 2 (a-y) and 3 (u-y), respectively, have been measured in 50% aqueous ethanol. The comparison of these values with those for the nine homomorphous a-, p-and y-acids, 4(a-y), 5(a-y) and 6(a-y), respectively, permits an evaluation of the steric effect of the (trimethy1)ammonio groups which is superimposed on their polar effect in the former acids. The pKl values, corrected for the steric effect, correlate very well with the reciprocal distance between the positive nitrogen atom and the dissociable proton. This confirms our earlier conclusion that the strength of these acids is determined by the field effect of the (trimethy1)ammonio groups only, the inductive model failing to account for the results. The distinction between two different transmission mechanisms for the polar effect therefore becomes unnecessary, the inductive model appearing as an atomistic description of the field effect.One of the prominent effects which determine the reactivity of organic molecules can be traced to the presence of charged or polar substituents. It is, therefore, of electrostatic origin and referred to as the polar effect. Two modes of transmission of this effect are usually distinguished, namely through the intervening bonds and atoms and directly through space or solvent [ 11. According to the former inductive model the substituent effect is propagated by successive polarization of bonds, the magnitude of the effect depending on the length and number of chains. The direct or field effect, however, is dependent on the distance and orientation of the substituent with respect to the reaction center. This dichotomy of transmission mechanisms for the polar effect appears to stem from the notion, clearly stated by Ingold [ 11, that the inductive effect is transmitted internally, i. e. through the molecule and that the field effect is transmitted externally, i.e. through the space immediately enveloping the molecule. In practice it is extremely difficult to distinguish between these two modes of transmission, the relative importance of which is still under dispute').') For reviews see [2].

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Section: Cfjh14cin06 (231636)mentioning

confidence: 99%

The Transmission of Polar Effects Polar Effects. Part II

Grob

Kaiser

Schweizer

1977

Helvetica Chimica Acta

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“…Grob developed a series of parameters (σ I(q) ) specifically for the inductive effects caused by substituents at the carbon bridgehead in quinuclidine derivatives . A series of these quinuclidines was prepared by simple modification of Grob's procedures, and the kinetic function of these amines in osmylation reactions was studied. Initially, the equilibrium constants for the coordination of the quinuclidines were measured.…”

Section: Introductionmentioning

confidence: 99%

Toward an Understanding of the High Enantioselectivity in the Osmium-Catalyzed Asymmetric Dihydroxylation. 4. Electronic Effects in Amine-Accelerated Osmylations

et al. 1997

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Electronic effects in osmylation reactions accelerated by pyridine and quinuclidine derivatives were investigated by varying the substituents on the amine ligand as well as on the alkene substrate. Ligand substituent effects were gauged by determination of the equilibrium constants for coordination of the amines to OsO 4 , evaluation of structural properties and reduction potentials of the amine-OsO 4 complexes, and analysis of the kinetics of osmylations in the presence of the amines. Substrate substituent effects were gauged by kinetic Hammett studies using several different amine/alkene combinations. Nonlinear Hammett relationships resulting from alkene substituent effects were observed, and the deviation from a linear free energy relationship was found to depend on the structure, binding capacity, and concentration of the amine. The results were evaluated in terms of the contending "[3 + 2]" and "[2 + 2]" mechanisms currently under consideration. A change in mechanism that depends on the structural and electronic properties of both alkene and amine is proposed.

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“…This mixture was stirred 10 min, then the hexane was separated, washed with 50 ml of water, and dried over anhydrous magnesium sulfate. The hexane was evaporated to yield 48 mg (73%) of an oil, 2-n-hexyl-2-methyl-7-butyrolactone, which was purified by chromatography: ir (CC14) 1776 cm"1; NMR (CC14) 0.8-2.2 (m, 15 ), 1.18 (s, 3 ), 4.12 (t, J = 8 Hz, 2 H); MS m/e (rel %) 184 (0.4), 169 (0.4), 113 (14), 100 (100), 70 (18), 55 (20); mol wt 184.14553 (caled for C,,H2o02, 184.14632).…”

Section: H)mentioning

confidence: 99%