Melting points are uncorrected. IR spectra (KBr or film) were carried out on a FT-Nicolet SX apparatus.'H NMR (300 MHz) and 13C NMR (75 MHz) spectra were recorded on a Varian VXR 300 spectrometer with TMS as internal standard. CDC1, was used as solvent for la, lb, and lc and CDC1,-DMSO-d6 for Id.