<sup>1</sup>H NMR study of the hetero‐association of unsaturated alcohols with pyridine

Lomas, John S.

doi:10.1002/poc.1953

Cited by 11 publications

(9 citation statements)

References 49 publications

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“…The corresponding alcohol, perfluoro- tert -butyl alcohol, has a p K a of 5.4, 28 so perfluoro- tert -butoxide is basic enough to deprotonate pivalic acid (p K a 5.0). 29 Additionally, the low boiling point of this perfluorinated alcohol (45 °C) 28 results in a high concentration of the base in solution and a low concentration of its conjugated acid at the reaction temperature of 120 °C. Furthermore, our group recently reported the ability of tetramethylammonium salts as iodide scavengers in palladium-catalyzed direct arylation.…”

Section: Results and Discussionmentioning

confidence: 99%

Ru-Catalyzed C–H Arylation of Fluoroarenes with Aryl Halides

et al. 2016

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Although the ruthenium-catalyzed C–H arylation of arenes bearing directing groups with haloarenes is well-known, this process has never been achieved in the absence of directing groups. We report the first example of such a process and show that unexpectedly the reaction only takes place in the presence of catalytic amounts of a benzoic acid. Furthermore, contrary to other transition metals, the arylation site selectivity is governed by both electronic and steric factors. Stoichiometric and NMR mechanistic studies support a catalytic cycle that involves a well-defined η6-arene-ligand-free Ru(II) catalyst. Indeed, upon initial pivalate-assisted C–H activation, the aryl-Ru(II) intermediate generated is able to react with an aryl bromide coupling partner only in the presence of a benzoate additive. In contrast, directing-group-containing substrates (such as 2-phenylpyridine) do not require a benzoate additive. Deuterium labeling and kinetic isotope effect experiments indicate that C–H activation is both reversible and kinetically significant. Computational studies support a concerted metalation–deprotonation (CMD)-type ruthenation mode and shed light on the unusual arylation regioselectivity.

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Section: Results and Discussionmentioning

confidence: 99%

Ru-Catalyzed C–H Arylation of Fluoroarenes with Aryl Halides

et al. 2016

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“…Indeed it has been reported that acetic acid suppresses alkene isomerization in Grubbs catalyzed metathesis reactions. In the self‐metathesis of 4‐PEA the substrate itself contains a weak acid (pKA=4.68 measured in water) that is also likely to have a suppressing effect on isomerization.…”

Section: Resultsmentioning

confidence: 99%

Bio–based Pentenoic Acids as Intermediates to Higher Value‐Added Mono‐ and Dicarboxylic Acids

et al. 2016

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The acid catalyzed reactive distillation of g-valerolactone yields pentenoic acids (PEAs) which can be obtained in > 90 % purity and > 97 % selectivity. The PEAs (five isomers) can be converted into a number of useful products with commercial relevance. The hydroxycarbonylation of PEAs yields adipic acid (a Nylon monomer) in very high selectivity and with good activity. Selfmetathesis of PEAs yields C6 -C8 unsaturated dicarboxylic acids which after hydrogenation produces a mixture of adipic acid, pimelic acid and suberic acid. If the PEAs are first subjected to ethenolysis; acrylic acid, 3-butenoic acid, and 4-pentenoic acid are produced. The self-metathesis of 3-butenoic acid produces b-hydromuconic acid in > 99 % selectivity which can be hydrogenated to adipic acid, whereas the self-metathesis of 4-PEA followed by hydrogenation gives suberic acid with 99 % selectivity. 3-Butenoic acid can also be hydroxycarbonylated to produce glutaric acid in 99 % selectivity.

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“…It is noteworthy that only a tiny amount (4%) of 6aa was produced in the presence of oxygen, while the reaction with iodomethyl pivalate quantitatively gave α-hydroxymethylated product 3 after 3 h under ordinary atmosphere (Scheme ). This is attributable to the stability of imidomethanolate D , an oxidized product of A that would supply formaldehyde more slowly than the PivOCH 2 O – formed in the reaction with iodomethyl pivalate because of the inferior leaving-group ability of the succinimide anion compared with the pivalate anion …”

Section: Resultsmentioning

confidence: 99%