Nuclear Overhauser effect difference

The use of reference deconvolution for the correction of artefacts in nuclear Overhauser effect difference spectroscopy [9] is illustrated by the spectra of fig. 3. The experimental technique used here differs slightly from that normally encountered in using a control spectrum in which the preirradiation is gated off rather than shifted in frequency, and in keeping the decoupler and transmitter at the same frequency. These modifications were... 

NUCLEAR OVERHAUSER EFFECT, DIFFERENCE SPECTROMETRY, H H PROXIMITY THROUGH SPACE 1 73... 

In Chapter 3 (Section 3.16), there is a description of the nuclear Overhauser effect difference experiment, an experiment that provides information about H— H through-space proximity. Review of this section is helpful before proceeding here. The ROESY experiment, rotating-frame Overhauser effect spectroscopy, is a useful 2-D analogue of the nuclear Overhauser effect difference experiment. This experiment is useful for molecules of all sizes whereas the related experiment, NOESY (nuclear Overhauser effect spectroscopy), is not very useful with small molecules. NOESY is used primarily with biological macromolecules. Both NOESY and ROESY experiments correlate protons that are close to each other in space, typically 4.5 A or less. 

The above data clearly suggest a dibenzazonine structure with two methoxyl and two hydroxyl groups as substituents, their locations being determined by nuclear Overhauser effect difference spectroscopy experiments (Fig. 1). Several derivatives of crassifolazonine (2) were prepared and characterized (2a-2c). Final proof for the proposed structure of crassifolazonine (2) was obtained by its total synthesis (15). 

Fig. 1. Nuclear Overhauser effect difference spectroscopy of crassifolazonine (2).

Nuclear Overhauser Effect Difference Spectrometry, H H Proximity Through Space 189... 

NOEDIF nuclear Overhauser effect difference spectroscopy... 

The most interesting work is the determination of stereochemistry of 5a and 5)3 diastereomers of (2a,3)5,3aa)-ethylperhydro-2-(l,2,3,4-tetraacetoxybutyl)-5,6,6-trimethylpyrrolo[l,2-Z)]isoxazole-3-carboxylate by use of ( H- H)COSY, ( C- H) HETCOR, and nuclear Overhauser effect difference spectroscopy (NOEDS) techniques <91MRC645>. 

Kotovych G, Aarts G H M 1982 Application of the nuclear Overhauser effect difference experiment assignment of the configuration of carboprostacyclin. Org Magn Res 18 77-81... 

Kinns, M. and Sanders, J. K. M. Improved frequency selectivity in nuclear Overhauser effect difference spectroscopy. /. Magn. Reson. 56 518-520, 1984. 

Neuhaus D, Rzepa HS, Sheppard RN, Bick IRC (1981) Assignment of the structure of dihydro-daphnine diacetate by nuclear Overhauser effect difference spectroscopy. Tetrahedron Lett 22 2933-2936... 

D. Wenhaus, R.N. Sheppard, and I.R.C. Bick, Structural and conformational study of repanduline using long-range nuclear Overhauser effect difference spectroscopy, J. Am. Chem. Soc. 105, 5996 (1983). 

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