All new compounds were characterized by standard spectroscopical and microanalytical methods.'H-NMR spectra were recorded on a Varian Gemini 300 spectrometer at 300 Mhz, using CDCI, or (CD,), SO as solvents and TMS as internal standard. Chemical shifts are reported in ppm downfield from the standard (6= 0.00). Elemental analyses were perfoxmed on a Heraeus CHN-Rapid Analyser. Melting points were determined on a Buchi 535 ...
