Long-range heteronuclear chemical shift correlation

Unlike HMBC /GHMBC and related long-range heteronuclear chemical shift correlation experiments, which have hundreds of reported applications in the published literature, there are considerably fewer reported applications of 1,1-ADEQUATE and related long-range variants in the literature. In part, the dearth of reported applications can be attributed to the considerably lower sensitivity of these experiments relative to, for example HMBC/GHMBC. Sensitivity concerns are largely ameliorated,... 

Long-range heteronuclear chemical shift correlations were observed for... 

Based on experience in one of the author s laboratories (GEM), cryogenic NMR probe technology may have the single biggest positive impact on increasing the facility with which long-range heteronuclear chemical shift correlation data may be acquired. 

Long-range Heteronuclear Chemical Shift Correlation... 

Martin GE, Zektzer AS (1988) Long-range two-dimensionalear heteronuclear chemical shift correlation. Magn Reson Chem 26 631-652 Massiot G, Nuzillard JM, Richard B, Le Men-Olivier L (1990) Alternative partial synthesis of bisindole alkaloids. Tetrahedron Lett 31 2883-2884 Meksuriyen D, Cordell GA (1988) Biosynthesis of staurosporine. 1. and C NMR assingments. J Nat Prod 51 884-892... 

As with any review, there will inevitably be examples that are not included for whatever reason. This has certainly been true with appUcations of long-range H— heteronuclear chemical shift correlation in the field of... 

In homonudear shift-correlation experiments like COSY we were concerned with the correlation of chemical shifts between nuclei of the same nuclear species, e.g., H with H. In heteronuclear shift-correlation experiments, however, the chemical shifts of nuclei belonging to different nuclear species are determined (e.g., H with C). These may be one-bond chemical shift correlations, e.g., between directly bound H and C nuclei, or they may be long-range chemical shift correlations, in which the interactions... 

The HMBC spectrum of vasicinone along with the H-NMR assignments are shown. Determine the H/ C long-range heteronuclear shift correlations based on the HMBC experiment, and explain how HMBC correlations are useful in chemical shift assignments of nonprotonated quaternary carbons. 

The HMBC spectrum of vasicinone displays long-range heteronuclear shift correlations between the various H/ C nuclei. These correlations are very helpful to determine the C-NMR chemical shifts of quaternary carbons and allow the interlinking of the different substructures obtained. 

COSY = homonuclear chemical shift correlation spectroscopy NOESY = 2D nuclear Overhauser effect (NOE) spectroscopy HMQC = heteronuclear mulltiple-quantum coherence RELAY = relayed coherence transfer COLOC = correlation via long-range coupling HMBC = heteronuclear long-range coupling INADEQUATE = incredible natural abundance double quantum transfer experiment. 

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