Long-range magnetic coupling

In the case of the other correlation shown in Figure 13 as an example, the m/cH long-range magnetization transfer occurs across the anticipated three bonds from the H8 doublet to the C6 quaternary aromatic carbon. Next, the nJcc correlation, rather than occurring via two- or three bonds where n = 2 or 3, instead is via an uncanceled [ fee coupling from C6 to Cl as shown by 44. 

Aside from the initial applications of the n, 1- and m,n-ADEQUATE experiments in the elucidation of the structure of 5,6-dihydrolamellarin (3, see Sections 4.1, 5.1 and 6.5), the author is unaware of any reported applications of these experiments in the literature.38 Given the potential ambiguities associated with the two long-range magnetization transfer steps of the latter, coupled with the very low sensitivity and the fact that correlations are observed in Fi at the DQ frequency of the coupled carbons rather than at the 13C shift as in the 1,1- or 1,h-ADEQUATE experiments, it is probably quite likely that the m,n-ADEQUATE experiment will continue to be very sparingly utilized for structure elucidation. 

Evolution of the Hr magnetization under the heteronuclear long-range scalar coupling nJCH... 

During the delay A, the proton coherence associated with long-range heteronuclear couplings is fully converted into anti-phase (AP) magnetization. The second 90° pulse applied on the 13C channel converts this AP magnetization into heteronuclear multiple quantum coherences (2HxCy). 

The proton magnetic resonance spectrum of l-cyano-l,2-dihydro-isoquinaldonitrile (8) has been reported" and is consistent with the assigned structure. A report on the long-range proton coupling in Reissert compounds has appeared. 

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