Abstract
The sensitivity of cryoprobes, which are rapidly becoming available, means that the measurement of coupling constants involving C-13, C-13 pairs at the natural abundance of C-13 can now, in principle, be done by using tens rather then hundreds of milligrams of compounds. However, a robust method that would yield reliable values of small long-range carbon--carbon coupling constants is still missing. In this Communication, we describe a novel C-13- detected incredible natural-abundance double-quantum transfer experiment (INADEQUATE) experiment for simultaneous correlation of one-bond and long-range C-13-C-13 pairs and the measurement of both types of coupling constants in C-13 natural abundance samples. This method yields accurate values of one-bond and long-range coupling constants by manipulation of pure phase in-phase (IP) and antiphase (AP) doublets, and is referred to as C-13-detected IPAP-INADEQUATE. It is illustrated by the measurement of interglycosidic (3)J(CCOC) coupling constants in a disaccharide molecule providing important information about the conformation of the glycosidic linkage. Owing to the simplicity of INADEQUATE spectra the carbon-carbon coupling constants are particularly suitable for studies of partially oriented molecules through the measurement of carbon-carbon residual dipolar couplings (RDCs). An example of this approach is presented. We expect the method to find a variety of applications in the conformational analysis of small molecules, determination of diastereoisomers and enantiomers, and studies of molecules in aligned media. Copyright (c) 2007 John Wiley & Sons, Ltd.
Original language | English |
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Pages (from-to) | 628-633 |
Number of pages | 6 |
Journal | Magnetic Resonance in Chemistry |
Volume | 45 |
Issue number | 8 |
DOIs | |
Publication status | Published - Aug 2007 |