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HSQC‐1, n ‐ADEQUATE: a new approach to long‐range 13 C 13 C correlation by covariance processing
Author(s) -
Martin Gary E.,
Hilton Bruce D.,
Robert Willcott III M.,
Blinov Kirill A.
Publication year - 2011
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.2793
Subject(s) - covariance , heteronuclear single quantum coherence spectroscopy , chemistry , heteronuclear molecule , sensitivity (control systems) , multiplicity (mathematics) , correlation , statistical physics , biological system , nuclear magnetic resonance spectroscopy , statistics , mathematics , stereochemistry , physics , mathematical analysis , engineering , electronic engineering , biology , geometry
Long‐range, two‐dimensional heteronuclear shift correlation NMR methods play a pivotal role in the assembly of novel molecular structures. The well‐established GHMBC method is a high‐sensitivity mainstay technique, affording connectivity information via n J CH coupling pathways. Unfortunately, there is no simple way of determining the value of n and hence no way of differentiating two‐bond from three‐ and occasionally four‐bond correlations. Three‐bond correlations, however, generally predominate. Recent work has shown that the unsymmetrical indirect covariance or generalized indirect covariance processing of multiplicity edited GHSQC and 1,1‐ADEQUATE spectra provides high‐sensitivity access to a 13 C 13 C connectivity map in the form of an HSQC‐1,1‐ADEQUATE spectrum. Covariance processing of these data allows the 1,1‐ADEQUATE connectivity information to be exploited with the inherent sensitivity of the GHSQC spectrum rather than the intrinsically lower sensitivity of the 1,1‐ADEQUATE spectrum itself. Data acquisition times and/or sample size can be substantially reduced when covariance processing is to be employed. In an extension of that work, 1, n ‐ADEQUATE spectra can likewise be subjected to covariance processing to afford high‐sensitivity access to the equivalent of 4 J CH GHMBC connectivity information. The method is illustrated using strychnine as a model compound. Copyright © 2011 John Wiley & Sons, Ltd.