General
1H NMR (500 MHz), 13C NMR (125 MHz) and 2D-NMR spectra were recorded on Fourier transform NMR spectrometer 500 MHz in CDCl3 with TMS as an internal standard. X-ray diffraction data were measured on a Bruker-Nonius kappaCCD diffractometer. Optical rotations were measured in CHCl3, using Perkin Elmer Polarimeter 341. The IR spectra were taken on Perkin Elmer 2000 infrared spectrometer with KBr disc. Melting points were recorded on Perkin Elmer DSC7 differential scanning calorimeter. The EI-MS and HR-EI-MS spectra were obtained on Thermo Finnigan MAT 95 XL mass spectrometer. Silica gel 60 (Merck, 70–230 mesh) or preparative thin-layer chromatography (prep-TLC): Kieselgel 60 PF254 (Merck. 0.5 mm) were used for chromatographic method.