Heteronuclear two‐and three‐dimensional nmr spectroscopy of ¹³C in natural abundance by multiplicity selection and editing: Application to peptides

Several new proton‐detected heteronuclear two‐dimensional (2D) nmr techniques are presented that exhibit the features of selection and editing of multiplicity. The theoretical basis of the new features is briefly discussed and the application of the 2D techniques to a thioanalogon of Cyclosporin A [Thio‐(1)‐cyclosporin A] is shown. In addition, an extension of the experiments to three‐dimensional (3D) techniques is demonstrated and the application of two 3D techniques to Thio‐(1)‐cyclosporin A with ¹³C in natural abundance is presented. The new techniques can help simplify heteronuclear shift correlations and increase the resolution in the carbon dimension.