Search results for ""Author Antony Williams""

The Ghanian plant Cryptolepis sanguinolenta is the source of a series of fascinating indoloquinoline alkaloids. The most unusual member of this alkaloid series was initially proposed to be a spiro nonacyclic structure, named cryptospirolepine, and was elucidated in 1993 based on the technologies available at that time. There were, however, several annoying attributes to the structure that bothered analysts for the ensuing 22 years. During the two decades that followed the initial work there have been enormous developments in NMR technology. Using new experimental approaches, specifically homodecoupled 1,1- and 1,n-HD-ADEQUATE NMR experiments developed in 2014, the structure of only a 700 µg sample of cryptospirolepine has been revised and is shown on the cover of this volume. The confluence of the NMR technological and methodological advances that allowed the revision of the structure of cryptospirolepine using a submilligram sample seems a fitting example for this book, which is dedicated to the NMR characterization of various classes of natural products. Volume 2 considers data processing and algorithmic based analyses tailored to natural product structure elucidation and reviews the application of NMR to the analysis of a series of different natural product families including marine natural products, terpenes, steroids, alkaloids and carbohydrates. Volume 1 discusses contemporary NMR approaches including optimized and future hardware and experimental approaches to obtain both the highest quality and most appropriate spectral data for analysis. These books, bringing together acknowledged experts, uniquely focus on the combination of experimental approaches and modern hardware and software applied to the structure elucidation of natural products. The volumes will be an essential resource for NMR spectroscopists, natural product chemists and industrial researchers working on natural product analysis or the characterization of impurities and degradation products of pharmaceuticals that can be as scarce as natural product samples.

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Strychnine’s poisonous nature was known in 16th century Europe, and the alkaloid was isolated in pure form for the first time in 1818. Then began a more than century-long quest to unravel the structure of strychnine that led to two Nobel prizes, clearly without the assistance of the modern spectroscopic methods to which we now have access. In his 1963 report of the synthesis, Woodward said, "The tangled skein of atoms which constitutes its molecule provided a fascinating structural problem that was pursued intensively during the century just past, and was solved finally only within the last decade." The structure elucidation of complex natural products is facilitated today by access to modern instrumentation and experimental techniques. Using a modern 600 MHz NMR spectrometer equipped with a 1.7 mm cryogenic probe and a 1 mg sample, it is now possible to acquire a comprehensive suite of 2D NMR spectra that rigorously characterizes the complex structure of strychnine in a scant 24 hours. When the 2D NMR data are combined with Computer-Assisted Structure Elucidation methods, the structure can be solved in mere seconds. It is against this historical backdrop that these two volumes regarding the Structure Elucidation of Natural Products by NMR is set. Volume 1 discusses contemporary NMR approaches including optimized and future hardware and experimental approaches to obtain both the highest quality and most appropriate spectral data for analysis. Volume 2 considers data processing and algorithmic based analyses tailored to natural product structure elucidation and reviews the application of NMR to the analysis of a series of different natural product families including marine natural products, terpenes, steroids, and carbohydrates. These books, bringing together acknowledged experts, uniquely focus on the combination of experimental approaches and modern hardware and software applied to the structure elucidation of natural products. The volumes will be an essential resource for NMR spectroscopists, natural product chemists and industrial researchers working on natural product analysis or the characterization of impurities and degradation products of pharmaceuticals that can be scarce as natural product samples.

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