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. 2016 Nov 28;55(51):15760–15765. doi: 10.1002/anie.201609481

Figure 4.

Figure 4

The structure of Z 1‐Me is strongly solvent‐dependent. 500 MHz 1H NMR spectra at 25 °C indicate that Z 1‐Me is present in monomeric form in [D6]DMSO (top) and as extensively hydrogen‐bonded and π‐stacked dimers (Z1‐Me) 2 in CDCl3 (middle), with a structure similar to the one observed in the crystal. The diagnostic signals of protons at low field, bound to N atoms or to the formyl C20 atom, are shown. Resonance assignments and intermodular NOE correlations observed in CDCl3 solutions of Z 1‐Me are visualized based on the crystal structure. The resonances originate from the major hydrogen‐bridged homodimer (Z1‐Me) 2 and the minor epimeric heterodimer (Z 1‐Me/epi‐Z 1‐Me), which contributes the eight satellite‐like bands. The epimerization site C82 is indicated with a pink star.