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Your search keyword '"McAlpine, James B."' showing total 10 results
Start Over Author "McAlpine, James B." Journal the journal of organic chemistry
10 results on '"McAlpine, James B."'

1. Toward Structural Correctness: Aquatolide and the Importance of 1D Proton NMR FID Archiving

Author

Pauli, Guido F, Niemitz, Matthias, Bisson, Jonathan, Lodewyk, Michael W, Soldi, Cristian, Shaw, Jared T, Tantillo, Dean J, Saya, Jordy M, Vos, Klaas, Kleinnijenhuis, Roel A, Hiemstra, Henk, Chen, Shao-Nong, McAlpine, James B, Lankin, David C, and Friesen, J Brent

Subjects
Inorganic Chemistry, Chemical Sciences, Bridged Bicyclo Compounds, Crystallography, X-Ray, Deuterium, Magnetic Resonance Spectroscopy, Molecular Structure, Protons, Sesquiterpenes, Medicinal and Biomolecular Chemistry, Organic Chemistry, Medicinal and biomolecular chemistry, Organic chemistry
Abstract

The revision of the structure of the sesquiterpene aquatolide from a bicyclo[2.2.0]hexane to a bicyclo[2.1.1]hexane structure using compelling NMR data, X-ray crystallography, and the recent confirmation via full synthesis exemplify that the achievement of "structural correctness" depends on the completeness of the experimental evidence. Archived FIDs and newly acquired aquatolide spectra demonstrate that archiving and rigorous interpretation of 1D (1)H NMR data may enhance the reproducibility of (bio)chemical research and curb the growing trend of structural misassignments. Despite being the most accessible NMR experiment, 1D (1)H spectra encode a wealth of information about bonds and molecular geometry that may be fully mined by (1)H iterative full spin analysis (HiFSA). Fully characterized 1D (1)H spectra are unideterminant for a given structure. The corresponding FIDs may be readily submitted with publications and collected in databases. Proton NMR spectra are indispensable for structural characterization even in conjunction with 2D data. Quantum interaction and linkage tables (QuILTs) are introduced for a more intuitive visualization of 1D J-coupling relationships, NOESY correlations, and heteronuclear experiments. Overall, this study represents a significant contribution to best practices in NMR-based structural analysis and dereplication.

Published
2016

6. Proton Fingerprints Portray Molecular Structures: Enhanced Description of the 1H NMR Spectra of Small Molecules

Author

Napolitano, José G., Lankin, David C., McAlpine, James B., Niemitz, Matthias, Korhonen, Samuli-Petrus, Chen, Shao-Nong, and Pauli, Guido F.

Abstract

The characteristic signals observed in NMR spectra encode essential information on the structure of small molecules. However, extracting all of this information from complex signal patterns is not trivial. This report demonstrates how computer-aided spectral analysis enables the complete interpretation of 1D 1H NMR data. The effectiveness of this approach is illustrated with a set of organic molecules, for which replicas of their 1H NMR spectra were generated. The potential impact of this methodology on organic chemistry research is discussed.

Published
2024
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7. Subtle Chemical Shifts Explain the NMR Fingerprints of Oligomeric Proanthocyanidins with High Dentin Biomodification Potency

Author

Nam, Joo-Won, primary, Phansalkar, Rasika S., additional, Lankin, David C., additional, Bisson, Jonathan, additional, McAlpine, James B., additional, Leme, Ariene A., additional, Vidal, Cristina M. P., additional, Ramirez, Benjamin, additional, Niemitz, Matthias, additional, Bedran-Russo, Ana, additional, Chen, Shao-Nong, additional, and Pauli, Guido F., additional

Published
2015
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10. Unprecedented Benzoquinone Motifs Reveal Post-Oligomerizational Modification of Proanthocyanidins

Author

Jing, Shu-Xi, Ferreira, Daneel, Pandey, Pankaj, Klein, Larry L., Chittiboyina, Amar Gopal, McAlpine, James B., Lankin, David C., Alania, Yvette, Reis-Havlat, Mariana, Bedran-Russo, Ana K., Chen, Shao-Nong, and Pauli, Guido F.

Abstract

Proanthocyanidins (PACs) are complex flavan-3-ol polymers with stunning chemical complexity due to oxygenation patterns, oxidative phenolic ring linkages, and intricate stereochemistry of their heterocycles and inter-flavan linkages. Being promising candidates for dental restorative biomaterials, trace analysis of dentin bioactive cinnamon PACs now yielded novel trimeric (1and 2) and tetrameric (3) PACs with unprecedented o- and p-benzoquinone motifs (benzoquinonoid PACs). Challenges in structural characterization, especially their absolute configuration, prompted the development of a new synthetic-analytical approach involving comprehensive spectroscopy, including NMR with quantum mechanics-driven 1H iterative functionalized spin analysis (HifSA) plus experimental and computational electronic circular dichroism (ECD). Vital stereochemical information was garnered from synthesizing 4-(2,5-benzoquinone)flavan-3-ols and a truncated analogue of trimer 2as ECD models. Discovery of the first natural benzoquinonoid PACs provides new evidence to the experimentally elusive PAC biosynthesis as their formation requires two oxidative post-oligomerizational modifications (POMs) that are distinct and occur downstream from both quinone-methide-driven oligomerization and A-type linkage formation. While Nature is known to achieve structural diversity of many major compound classes by POMs, this is the first indication of PACs also following this common theme.

Published
2023
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