Quinone Methides. Base-Catalyzed Condensation Reactions of Hydroxybenzyl Alcohols and Ethers

Merijan, Ashot; Gardner, Pete D.

doi:10.1021/jo01022a523

Cited by 38 publications

(13 citation statements)

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“…The self‐condensation reactivity of the alkali metal salts of 2‐HMP and 4‐HMP is directed to the electron density at the 2 and 4 hydroxymethyl substituted ring positions. The condensation kinetic rates will be dependent on the electron density at the reaction sites and the particular mechanism involved, which is thought to be mediated by a QM mechanism . The resonance structures of QMs that can form from 2‐HMP and 4‐HMP are shown in Fig.…”

Section: Discussionmentioning

confidence: 99%

Chemical shifts of phenolic monomers in solution and implications for addition and self‐condensation

Haupt

Renneckar

2012

Magnetic Reson in Chemistry

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Alkali metal counter-cations alter the electron density of phenolates in solution by electrostatic interactions. This change in electron density affects their reactivity toward formaldehyde, hydroxymethylphenols, and isocyanates during polymerization. The electronic perturbation of phenolic model compounds in the presence of alkali metal hydroxides was investigated with (13)C and (1)H nuclear magnetic resonance in polar solvents relative to non-ionic controls, altering the chemical shifts of the model compounds, thus indicating changes in electron density using the chemical shift as a proxy. These shifts were attributed to Coulombic electrostatic interactions of the counter-cation with the phenolate anion that correlated to hydrated ionic radius and solvent dielectric constants. The predicted relative reaction rates for formaldehyde addition based on electron density ranking from (13)C nuclear magnetic resonance of the phenolic models was compared with the literature values. Predictions for condensation reactions of 2- and 4-hydroxymethylphenol from chemical shifts were consistent with published results. The results permit predictions for the reaction of phenolic compounds for the formation of thermosetting polymeric materials.

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Section: Discussionmentioning

confidence: 99%

Chemical shifts of phenolic monomers in solution and implications for addition and self‐condensation

Haupt

Renneckar

2012

Magnetic Reson in Chemistry

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“…1,18 Previously, the parent ortho -quinone methide was only observed via NMR spectroscopy at −100 °C. 19–22 The treatment of the oxo-η 5 -dienyl iridium complex 6 with t- BuOK/CH 2 Cl 2 at room temperature afforded a yellow microcrystalline η 4 - o -quinone methide complex 7 (eq. 2).…”

Section: Os- and Ir-mediated Ortho-quinone Methide Generationmentioning

confidence: 99%

Applications of ortho-Quinone Methide Intermediates in Catalysis and Asymmetric Synthesis

2011

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Ortho -quinone methides are important synthetic intermediates and widely implicated in biological processes. In this Synopsis, recent advances concerning the synthesis and utility of these intermediates are discussed with a particular emphasis on metal-catalyzed formation of quinone methide intermediates. Additionally, applications of these intermediates as partners in asymmetric synthesis will be discussed including methods we have developed that involve the enantioselective Pd-catalyzed formation of ortho-quinone methides, and the trapping of aforementioned intermediates with diverse nucleophiles.

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“…NMR data (Table 1) in combination with mass spectrometric data from GC‐MS (Table 2) showed that this compound was 2‐(2‐hydroxybenzyl)malonic acid (HBMA, Fig. 1) [19]. NMR analysis of P. centrifuga crude culture samples originally containing 0.1 mM 3‐CCA demonstrated that approximately 90% of the 3‐CCA was converted to HBMA during the incubation.…”

Section: Resultsmentioning

confidence: 98%

Fungal modification of the hydroxyl radical detector coumarin-3-carboxylic acid

Iakovlev

Broberg

Stenlid

2003

FEMS Microbiology Ecology

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The feasibility of using coumarin-3-carboxylic acid (3-CCA) for detection of hydroxyl radicals in pure cultures of wood-decaying fungi was tested. Fungi were incubated on a 3-CCA-containing medium. The transformation of 3-CCA to the fluorescent hydroxyl radical detector substance 7-hydroxycoumarin-3-carboxylic acid and other compounds was studied by chromatographic and spectroscopic techniques. During incubation of all tested fungi, a small fraction of the 3-CCA was hydroxylated to 7-hydroxycoumarin-3-carboxylic acid and a major fraction of the 3-CCA was metabolized by fungi to 2-(2-hydroxybenzyl)malonic acid. In most cultures the concentration of 3-CCA was below detection limit at the end of incubation. The fungal metabolism was suggested to be involved in the formation of 2-(2-hydroxybenzyl)malonic acid from 3-CCA, consequently making this method of hydroxyl radical detection less suitable to use on cultures of wood-decaying fungi.

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Quinone Methides. Base-Catalyzed Condensation Reactions of Hydroxybenzyl Alcohols and Ethers

Cited by 38 publications

References 1 publication

Chemical shifts of phenolic monomers in solution and implications for addition and self‐condensation

Chemical shifts of phenolic monomers in solution and implications for addition and self‐condensation

Applications of ortho-Quinone Methide Intermediates in Catalysis and Asymmetric Synthesis

Fungal modification of the hydroxyl radical detector coumarin-3-carboxylic acid

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