反应详情

To a solution of 2(R)-[(3,4-methylenedioxybenzyl)-(4-methoxy-2,3,6-trimethylbenzenesulfonyl)amino]-3-methylbutyric acid (3.82 g, 8.24 mmol) in dry methylene chloride (20 mL) was added oxalyl chloride (2.2 mL, 24.72 mmol) and a drop of dimethylformamide. The reaction mixture was stirred for 4 h and then concentrated. The residue was dissolved in methylene chloride 20 mL) and N,O-bis-trimethylsilylhydroxylamine (8.8 mL, 41.2 mmol) was added. After 4 h, methanol (1 mL) was added and the stirring was continued for 30 min. Silica gel (10 g) was added and the material was concentrated to dryness. The resultant powder was flash chromatographed on a silica gel column and eluted with 50% ethyl acetate/hexanes to give N-hydroxy-2(R)-[(3,4-methylenedioxybenzyl)-(4-methoxy-2,3,6-trimethylbenzenesulfonyl)amino]-3-methylbutyramide (2.46 g).

1. concentrationconcentrated
2. additionwas added
3. waitAfter 4 h
4. waitthe stirring was continued for 30 min
5. additionSilica gel (10 g) was added
6. concentrationthe material was concentrated to dryness
7. customchromatographed on a silica gel column
8. washeluted with 50% ethyl acetate/hexanes