Amino acids as selective sulfonamide acylating agents

The chloroform soluble extract (8.5 g) was chromatographed on silica gel column using CHCl 3 , and the polarity was increased with MeOH.. trimestris (18 g) was chromatographed

over silica gel using hexane containing increasing amounts of EtOAc.. afforded sitosterol (27.2 mg, 0.005%), eluted

The crude reaction mixture was evaporated under reduced pressure and the residue was purified by column chromatography over silica gel eluting with hexane-ethyl acetate (4:1 to

The crude salt was chromatographed on a silica gel column using a mixture of dichloromethane and methanol (9.5:0.5) as eluant. The residue obtained was purified by precipitation

After the usual work up, with sodium carbonate (10%), the reaction residue, a complex mixture of products, was submitted to chromathography in a silica gel column, using

The organic phase was separated, dried over MgSO 4 , filtered, the solvent was evaporated, and the residue was purified by column chromatography through silica gel, using

The solvent was evaporated and the crude product was purified by column chromatography on silica gel using hexane: EtOAc (9:1) as eluent, to afford 2 in 74% yield as a colorless

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