2 Experimental
2.1 General experimental procedures
NMR spectra were recorded on a Bruker ACF-500/300
NMR instrument (1
H: 500/300 MHz, 13C: 125/75 MHz) with
TMS as internal standard. Mass spectra were obtained on a
MS Agilent 1100 Series LC/MSD Trap mass spectrometer
(ESI-MS) and a Micro Q-TOF MS (HRESIMS), respectively.
All solvents used were of analytical grade (Tianjin Chemical
Plant). Column chromatography was performed on silica gel
(100í200 mesh, 200í300 mesh, Qingdao Marine Chemical
Co., Ltd.) and Sephadex LH-20 (Pharmacia).