Ring-chain tautomerism. Part 8. Substituted 2-(2-oxopropyl) and 2-(2-oxo-2-phenylethyl)benzoic and 2-(2-acetyl and 2-benzoylphenyl)acetic acids

Bowden, Keith; Byrne, Jane M.

doi:10.1039/p29960001921

Cited by 8 publications

(3 citation statements)

References 7 publications

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“…This scenario rationalizes the nondetectable NMR signals of the 16-H 2 or 16C, 17C, and the expected couplings (e.g., between 4 and 16, 16 and 18, and 17 and 18) . Such an “open chain-ring tautomerism” has previously been reported for more simple hydroxylactones. − Continuous interconversion between the ring and the open chain tautomeric forms hampered the interpretation of the spectra. Thus, the signals of the lactone ring were only very weak (e.g., the NMR signals C2, C3, C15−C17, or 16-H 2 , see Table ).…”

Section: Resultssupporting

confidence: 76%

“…56 Such an "open chain-ring tautomerism" has previously been reported for more simple hydroxylactones. [57][58][59] Continuous interconversion between the ring and the open chain tautomeric forms hampered the interpretation of the spectra. Thus, the signals of the lactone ring were only very weak (e.g., the NMR signals C2, C3, C15-C17, or 16-H 2 , see Table 2).…”

Section: Resultsmentioning

confidence: 99%

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Molecular Analysis of the Benastatin Biosynthetic Pathway and Genetic Engineering of Altered Fatty Acid−Polyketide Hybrids

Schenk

Hertweck

2007

J. Am. Chem. Soc.

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The entire gene locus encoding the biosynthesis of the potent glutathione-S-transferase inhibitors and apoptosis inducers benastatin A and B has been cloned and sequenced. The cluster identity was unequivocally proven by deletion of flanking regions and heterologous expression in S. albus and S. lividans. Inactivation and complementation experiments revealed that a KSIII component (BenQ) similar to FabH is crucial for providing and selecting the rare hexanoate PKS starter unit. In the absence of BenQ, several novel penta- and hexacyclic benastatin derivatives with antiproliferative activities are formed. In total, five new compounds were isolated and fully characterized, and the chemical analysis was confirmed by derivatization. The most intriguing observation is that the ben PKS can utilize typical straight and branched fatty acid synthase primers. If shorter straight-chain starters are utilized, the length of the polyketide backbone is increased, resulting in the formation of an extended, hexacyclic ring system reminiscent of proposed intermediates in the griseorhodin and fredericamycin pathways. Analysis and manipulation of the hybrid fatty acid polyketide pathway provides strong support for the hypothesis that the number of chain elongations is dependent on the total size of the polyketide chain that is accommodated in the PKS enzyme cavity. Our results also further substantiate the potential of metabolic engineering toward polyphenols with altered substituents and ring systems.

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Section: Resultssupporting

confidence: 76%

Section: Resultsmentioning

confidence: 99%

Molecular Analysis of the Benastatin Biosynthetic Pathway and Genetic Engineering of Altered Fatty Acid−Polyketide Hybrids

Schenk

Hertweck

2007

J. Am. Chem. Soc.

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“…Related ring-chain tautomerisms have been investigated by Bowden and Byrne. 12 By means of 1 H-NMR and pK a -measurements it was concluded that molecules of the general structure 9 (Scheme 4) also reside mainly in their chain forms. However, 13 C-NMR data (in CDCl 3 ) did, in some cases, show additional Very recently a study of the dynamic ring-chain behaviour of the bislactam N-(2-aminoacetyl)-2-pyrrolidone has been published, in which cyclol forms are discussed.…”

Section: Resultsmentioning

confidence: 99%

Products from dehydration of dicarboxylic acids derived from anthranilic acid

2003

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Treatment of N-(carboxymethyl)-anthranilic acids 1 with several dehydrating agents, gave the cyclic ortho amides 6, or the 7-membered anhydrides 7. After reaction of N-(carboxymethyl)-anthranilic acid (1a) with acetic anhydride, a diacetylated fused diketopiperazine indole dimer (18) could be isolated. Dehydrations of 2,2'-iminobis-benzoic acid led to the corresponding cyclic ortho amides 23. The dynamic behaviour of some of these compounds, and their precursors, was studied.

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Ab initio and Density Functional Calculations on the Ring-Chain Tautomerism of γ-Oxocarboxylic Acids

Fabian

Bowden

2001

Eur. J. Org. Chem.

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Keywords: Ab initio calculations / γ-Oxocarboxylic acids / Density functional calculations / Substituent effects / Tautomerism The results of ab initio (HF, MP2) and density functional (B3LYP) calculations on a series of γ-oxocarboxylic acids [(Z)-3-acetyl or benzoylacrylic and 2-acetyl or benzoylbenzoic acids] A and their cyclic tautomers B are presented. For the open-chain tautomers, different rotamers were considered.Bulk solvent effects were considered by using the polarised continuum model (PCM) and were found to be essential for a [a]

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Ring-chain tautomerism. Part 8. Substituted 2-(2-oxopropyl) and 2-(2-oxo-2-phenylethyl)benzoic and 2-(2-acetyl and 2-benzoylphenyl)acetic acids

Cited by 8 publications

References 7 publications

Molecular Analysis of the Benastatin Biosynthetic Pathway and Genetic Engineering of Altered Fatty Acid−Polyketide Hybrids

Molecular Analysis of the Benastatin Biosynthetic Pathway and Genetic Engineering of Altered Fatty Acid−Polyketide Hybrids

Products from dehydration of dicarboxylic acids derived from anthranilic acid

Ab initio and Density Functional Calculations on the Ring-Chain Tautomerism of γ-Oxocarboxylic Acids

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