HSQC-1,n-ADEQUATE: a new approach to long-range 13C13C correlation by covariance processing

✍ Scribed by Gary E. Martin; Bruce D. Hilton; M. Robert Willcott III; Kirill A. Blinov

• Publisher: John Wiley and Sons
• Year: 2011
• Tongue: English
• Weight: 302 KB
• Volume: 49
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.2793

✦ Synopsis

Abstract

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.