In Paris (Univ. Descartes) 1H- and 13C-NMR spectra (500.13MHz and 125.77MHz, respectively) were recorded on a Bruker Avance500 spectrometer in DMSO-d6 or acetone-d6 solvents. All NMR spectra were measured at 20 ◦C, and proton and carbon chemical shifts were referenced to the solvent signals: 2.50ppm for proton and 39.52ppm for carbon in DMSO-d6, and 2.05ppm for proton and 29.85ppm for carbon in (CD3)2CO. Two-dimensional correlation spectroscopy (COSY) and total correlation spectroscopy (TOCSY)