All chemicals were obtained from the supplier and used without further purification. Dry solvents were prepared by common laboratory methods. The eluents for chromatography petroleum ether (low-boiling) and ethyl acetate were distilled prior to use.Thinlayer chromatography silica gel 60 F254 glass plates (layer thickness of 0.20 mm on aluminium, pore size 60 Å) from the company Merck were used. Column chromatography