*3.1. General experimental procedures*

ESI-MS experiments were performed on an Applied Biosystem API 2000 triplequadrupole mass spectrometer. High Resolution ESI-MS spectra were performed on a Thermo Orbitrap XL mass spectrometer. All the mass spectra were recorded by infusion into the ESI source using MeOH as the solvent. CD spectra were recorded in MeOH solution on a Jasco J-710 spectrophotometer using a 1 cm cell. 1H and 13C NMR spectra were determined in C6D6 solution on a Varian UnityInova spectrometer at 700 and 175 MHz, respectively; chemical shifts were referenced to the residual solvent signal (ΈH 7.15, ΈC = 128.0). For an accurate measurement of the coupling constants, the one-dimensional 1H NMR spectra were transformed at 64K points (digital resolution: 0.09 Hz). Homonuclear 1H connectivities were determined by COSY experiments. Through-space 1H connectivities were evidenced using a ROESY experiment with a mixing time of 500 ms. The reverse multiple-quantum heteronuclear correlation (HMQC) spectra was optimized for an average 1*J*CH of 142 Hz. The gradient-enhanced multiple-bond heteronuclear correlation (HMBC) experiment was optimized for a 3*J*CH of 8.3 Hz. 
