1 General experimental details 1H NMR and 13 C NMR spectra were measured on 400 MHz spectrometer, using CDCl3 as the solvent with tetramethylsilane(TMS) as the internal standard at room temperature. Chemical shifts(δ) are given in ppm relative to TMS, the coupling constants J are given in Hz. HRMS were recorded on a TOF LC/MS equipped with electrospray ionization(ESI) probe operating in positive or negative ion mode.
