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April 27, 2006, ACD/Labs ENC 2006, Pacific Grove, CA, USA
Automated Evaluation of a Chemical Structure with Only 1D 1H and 2D 1H-13C HSQC
Sergey S. Golotvin, Eugene Vodopianov, Rostislav Pol, Brent A. Lefebvre, Antony J. Williams, and Timothy D. Spitzer
Abstract
As NMR instrumentation continues to advance, 2D experiments that once took hours are now achievable in minutes. With the standard 1H-13C HSQC experiment now possible in a matter of 8 to 10 minutes, this experimental data set is now useful when a high-throughput evaluation of a proposed chemical structure is necessary. With the additional information that this experiment can provide, much benefit can be gained in the automated evaluation of a proposed chemical structure.
In this work we present a new method of automatic structure validation based on the comparison of calculated and experimental data that is available in a 1D 1H NMR spectrum and a 2D 1H-13C HSQC. Following the approach developed in our previous work on 1D 1H spectra only, a comparison is made by means of assignment of the spectral signals calculated for a proposed structure to those which are observed in the experimental NMR spectrum. The peaks in the 2D NMR spectrum greatly increase the accuracy of this assignment process and therefore the structure validation, because they contain both the 1H and 13C chemical shifts of the connected nuclei. The advantages also extend into the ability of the 2D spectrum to improve the analysis of overlapping multiplets in the 1D spectrum and identify the protons attached to heteroatoms in the 1D spectrum since these do not show up at all in the 2D spectrum.
All of these factors combine to produce an automated system that can greatly outperform a system where 1D 1H information alone is used. Using dozens of real-life spectrum sets, it was possible to unambiguously identify no less than 90% of the correct structures. As part of this test, incorrect structures were also matched with each spectrum set. In this case, the structures were mainly regioisomers of the correct structures, so as to offer a challenging test of the specificity of the system. For these incorrect structures the false positive rate was observed as low as 1%.
Download the poster in Adobe Acrobat format (354 Kb PDF file).
Relevant Products: ACD/2D NMR Expert, ACD/Automation Server
Relevant Solutions: Structural Verification and Spectral Confirmation;
Analysis and Processing of Spectroscopic Data
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