J. Braz. Chem. Soc. vol.21 número1

The solvent was evaporated in vacuum and the resulting product was purified by column chromatography on silica gel (hexane-EtOAc, gradient of polarity), to give compound 7 (8.8

rt, the solvent was evaporated under reduced pressure and the residue thus obtained, was purified by column chromatography using pentane:Et 2 O (9:1) to give ( S )-3 as a

The reaction mixture was kept 8 h at rt and then DMF was distilled under reduced pressure and the crude product was puriied by column chromatography on silica gel (20% CHCl 3

Fraction 8 (1.0 g), collected with ethyl acetate, was chromatographed in a silica gel CC and fractions analyzed by silica gel TLC

After the completion of the reactions, the systems were cooled to room temperature, and the mixture was subjected to silica gel lash column chromatography (ethyl

After completion of the reaction, which was monitored by TLC, the solid product was collected by iltration, washed with water and aqueous ethanol and puriied

Traditional purification of these reaction products by silica gel column chromatography demanded a large amount of solvent and time, besides allowing the irreversible adsorption

After the complete reaction, the mixture was brought to room temperature and was directly filtered through silica gel, using hexane/ethyl acetate (7:3) as solvent and the