Selection of methyl resonances in proton-detected heteronuclear shift correlation, the HQQC experiment
H. Kessler, P. Schmieder, M. Koeck, M. Reggelin
J. Magn. Reson. (1991) 91, 375-379
The heteronuclear quadruple quantum coherence (HQQC) technique for selection of XH3 groups in 2-dimensional NMR spectroscopy is presented. The pulse sequence differs from heteronuclear triple quantum coherence only in the phase cycle; the selection of quadruple-quantum coherence is achieved by incrementing the phase of the last proton 90° pulse and the receiver in 60° steps. For C, the selection of Me resonances is possible with the HQQC experiment, with a dramatic reduction of the spectral width with a concomitant increase in resolution and decreased measuring time compared with the conventional heteronuclear multiple quantum coherence experiment Illustrative experimental results on application of HQQC to thio-(1)-cyclosporin A are presented.