Reaktions‐Geschwindigkeit aliphatischer Säurehalogenide

Leimu, R.

doi:10.1002/cber.19370700534

Cited by 37 publications

(10 citation statements)

References 17 publications

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“…As communicated earlier,18 the decarboxylation of the acid 8 was particularly rapid in rigorously dried DMF solutions, and the decarboxylated anthraquinone 9 was isolated in 79 % yield after stirring for 12 h at 40 °C. The poor nucleophilicity of the strongly chelated phenolic hydroxy group at C‐1 in 9 in the esterification with the racemic α‐branched acyl chloride 10 20 was overcome by addition of 4‐(dimethylamino)pyridine (DMAP)21 to afford the ester 11 in 95 % yield. The key step was the subsequent Baker–Venkataraman rearrangement induced by heating of the ester 11 under reflux with lithium hydride to afford the anthraquinone 12 with a branched β‐diketo side chain in 97 % yield.…”

Section: Resultsmentioning

confidence: 99%

“…2‐Methylbutanoyl Chloride (10): 20 2‐Methylbutanoic acid (20.0 g, 196 mmol) was treated with thionyl chloride (26.2 g, 220 mmol, 16.0 mL) and a few drops of DMF. The reaction started spontaneously and the mixture was stirred for 2 h at 40 °C.…”

Section: Methodsmentioning

confidence: 99%

“…The crude product was distilled to afford the acid chloride as a colorless oil (17.4 g, 85 %, b.p. 32 °C/1 mbar (ref 20. b.p.…”

Section: Methodsmentioning

confidence: 99%

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Total Synthesis ofrac‐γ‐Indomycinone by Baker–Venkataraman Rearrangement

et al. 2007

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Keywords:Total synthesis / Anthrapyranone antibiotics / γ-Indomycinone / Baker-Venkataraman rearrangement / Radical brominationThe total synthesis of racemic γ-indomycinone (rac-3) was achieved by Baker-Venkataraman rearrangement of ester 11 to the diketone 12, acid-catalyzed cyclization to the anthrapyranone 13, followed by methyl ether cleavage and acetylation to 16, selective bromination of the branched side chain with simultaneous S N 1-type hydroxy substitution to 23 and

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Total Synthesis ofrac‐γ‐Indomycinone by Baker–Venkataraman Rearrangement

et al. 2007

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“…Early studies by other groups favored competing S N 1 and S N 2 pathways for the alkyl chloro-, chlorothio-, chlorothiono-, and dithiochloroformates [ 50 – 59 ]. Upon evaluating the rates of hydrolysis in aqueous solvents, Queen [ 54 – 55 ] suggested that with increasing electron donation to the chlorocarbonyl group in alkyl chloro- and chlorothioformates, the positive entropies and low solvent isotope effects pointed to a mechanism involving a unimolecular acyl–halogen bond fission.…”

Section: Introductionmentioning

confidence: 99%

Kinetic evaluation of the solvolysis of isobutyl chloro- and chlorothioformate esters

D’Souza¹,

McAneny²,

Kevill³

et al. 2011

Beilstein J. Org. Chem.

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SummaryThe specific rates of solvolysis of isobutyl chloroformate (1) are reported at 40.0 °C and those for isobutyl chlorothioformate (2) are reported at 25.0 °C, in a variety of pure and binary aqueous organic mixtures with wide ranging nucleophilicity and ionizing power. For 1, we also report the first-order rate constants determined at different temperatures in pure ethanol (EtOH), methanol (MeOH), 80% EtOH, and in both 97% and 70% 2,2,2-trifluoroethanol (TFE). The enthalpy (ΔH≠) and entropy (ΔS≠) of activation values obtained from Arrhenius plots for 1 in these five solvents are reported. The specific rates of solvolysis were analyzed using the extended Grunwald–Winstein equation. Results obtained from correlation analysis using this linear free energy relationship (LFER) reinforce our previous suggestion that side-by-side addition–elimination and ionization mechanisms operate, and the relative importance is dependent on the type of chloro- or chlorothioformate substrate and the solvent.

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“…Incorporation of sulfur within the alkoxy (or phenoxy) group favors an increased participation by the ionisation mechanism in its competition with the addition±elimination pathway. 2,3 In the present study, the solvolyses of methyl chloroformate 9,17,18 are investigated. First-order speci®c rates of solvolysis measured at, or extrapolated to, 40.0 8 8C are reported in Table 1 for a variety of pure and binary solvent mixtures.…”

mentioning

confidence: 99%