When we undertook the work to write a review article on CASE Systems (computer-assisted structure elucidation) at the invitation of the Progress in NMR Spectroscopy editors we didn’t envisage almost 2 years of work. Adding a review article into an 80 hour work week, balancing with family, blah, blah, blah wasn’t quite sane. By the end it went from a labor of love to a burden. However, the last pangs of pain all washed away tonight when we heard that it’s online
Computer-assisted Structure Verification and Elucidation Tools In NMR-Based Structure Elucidation (Reference: JPNMRS1239) in Progress in Nuclear Magnetic Resonance Spectroscopy is alive and well and living at http://dx.doi.org/10.1016/j.pnmrs.2007.04.003.
For those of you who have been watching the hexacyclinol controversy (1,2,3,4,5,6) we just worked with John Porco’s group and used a CASE approach to generate the correct assignments for the molecule. The work is presently being submitted for publication under the following abstract.
“Computer-Assisted Structure Elucidation (CASE) using a combination of 1D and 2D NMR data has been available for a number of years. These software programs can be considered as logic machines capable of deriving all plausible structures from a set of structural constraints or â€œaxiomsâ€, these being produced from the spectral data and associated chemical information or prior knowledge. CASE programs allow the spectroscopist not only to determine the structures from the spectral data but also to study the dependence of the solution on changes to the set of axioms. In this article we describe the application of the ACD/Structure Elucidator expert system to resolve the conflict between two different hypothetical hexacyclinol structures derived by different researchers from the NMR spectra of this complex natural product. It has been shown that the combination of algorithms for both structure elucidation and structure validation delivered by the expert system enables the identification of the most probable structure as well as the associated chemical shift assignment.”
The final assignments are shown below, together with some of the correlations used to generate the assignment.