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September 10, 2006, SMASH 2006, Burlington, VT, USA
On the Importance of Structure Stereochemical Markers in 13C NMR Predictions
Ryan R. Sasaki, Brent A. Lefebvre
Abstract
More than half of all approved drugs contain stereocenters. In fact, stereocenters impact a significant amount of compounds in virtually all chemical industry fields, from perfumes to flavors, agrochemicals to specialty polymers, and more. We know that small stereochemistry variations can mean the difference between a commercially viable and worthless compound, or even between a safe compound or a toxic one. For this reason, when using NMR predictions to assist in structure verification, the stereochemistry within a structure should always receive special attention. However, drawing a structure in a stereochemically accurate fashion can take substantial additional efforts, so that it is not uncommon for some of the stereocenters to be left undefined. What is the impact of such omissions on the ability to verify and interpret the structure-spectrum relationships from a stereochemically valid point of view?
The purpose of this study is to validate the importance of drawing stereochemical markers on chemical structures prior to 13C NMR predictions. Much like in real-word situations, the 13C chemical shifts are heavily impacted by their stereochemical orientation. A structurally diverse dataset was used to compare the accuracy of the 13C chemical shifts of over 50 compounds with and without stereochemistry drawn. The results of this study reveal that it is absolutely critical to include stereochemical markers before generating a prediction. This poster will highlight the accuracy results of this study and provide information on how ACD/Labs NMR prediction algorithms handle these special cases.
Download the poster in Adobe Acrobat format (137 Kb PDF file).
Relevant Products: CNMR Predictor, CNMR DB
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