Copyright©2007 Antony Williams
There have been a number of discussions flying around blogspace recently about NMR Prediction Algorithms. Very interesting to watch and primarily focused on C13 NMR prediction.
Last night I finished up proofing a chapter written with a friend and colleague, Gary Martin, on the applications of N15 NMR in Alkaloid Chemistry for a book to be published by Wiley in the near future (Modern Alkaloids, Structure, Isolation, Synthesis and Biology, Fattorusso, E. / Taglialatela-Scafati, O. (eds.)).
Gary has certainly been my mentor on N15 NMR in recent years as well as providing me with weekly updates to tantalize my eyes..he is a PHENOMENAL photographer.
The book cover is shown below…it will likely become a definitive reference text for alkaloids chemists.
During the process of writing this book chapter we had the opportunity to test the performance of N15 NMR prediction algorithms using the program I have access to, ACD/NNMR Predictor.
Suffice to say, the performance was excellent. A plot of observed vs. calculated 15N chemical shifts for forty-nine 15N chemical shifts from the review article is shown below. These chemical shifts and associated compounds are not contained within the training set.
Regression analysis delivered: R2 = 0.987. Further details of the analysis will of course be in the book (I don’t get any royalties honestly!).
The results are in alignment with those we obtained when examining the performance of P-31 NMR prediction for a book I co-authored “Practical Interpretation of P-31 NMR Spectra and Computer-Assisted Structure Verification“.
XNMR prediction is not as refined as C13 NMR or even H1 NMR prediction for sure…the datasets are MUCH smaller than the more common nuclei and the algorithms are not yet optimal. However, XNMR prediction certainly provides value…and if nothing else, keep me up at night with the other passionate NMR jocks in the world clicking on the keyboard…Stumble it!