Figure 5.

Optimizing processing parameters reveal coupling constants and line counts present in the signals for H-5a and H-6 of 1b. Double zero filling was applied to both. The bottom (blue) signals were obtained using a Lorentzian–Gaussian apodization function of LB = −1.4 Hz and GF = 0.17 (17% AQ). The top (black) signals resulted from a Lorentzian–Gaussian apodization function of LB = −2.5 Hz and GF = 0.25 (25% AQ) and demonstrate that all theoretical lines of these complex “multiplets” can indeed be deciphered by manual analysis facilitated by tools such as jVisualizer (http://jvisualizer.sourceforge.net/). Actually, proton H-5a resonates as a ddddq, and H-6 gives rise to a ddq signal.