fig1

Figure 1. Part of the ¹H NMR (600 MHz, CDCl₃, 22 ^oC) spectra of (S)-7 (A); (S)-8 (B); (R)-8 (C); (R)-7 (D) and experimental ESI-MS of the (S)-8 of [8+2H]²⁺ (blue) and simulated mass spectra (red) (E).