1 H and C NMR spectra were recorded on a Bruker Avance Spectrometer (400 or 500 MHz, 100 or 125 MHz respectively). FT-IR spectra in attenuated total ref lection mode were recorded on a Thermo Scientif ic model Nicolet iS5 spectrometer using an iD7 attachment. HRMS was carried out on an Agilent model G6520 Q-TOF instrument in ESI mode with a Maxis-TOF analyser.