反应详情

To a solution of piperidine-1,4-dicarboxylic acid mono-tert-butyl ester (2.06 g, 9 mmol), NEt3 (1.2 g, 12 mmol) in toluene (150 mL) was added isobutylchloroformate (1.23 g, 9 mmol) at 0° C. The mixture was stirred at room temperature for 1.5 hours. N-hydroxy-2-(4-methanesulfonyl-phenoxy)-acetamidine (1.5 g, 6 mmol) was added to the mixture. The mixture was heated under reflux overnight, cooled and the mixture was washed successively with H2O and brine. After drying (Na2SO4), the solvent was removed. The residue was purified by flash chromatography on silica gel to afford the desired product. 1H NMR (CDCl3): δ 7.98 (2H, m), 7.14 (2H, m), 5.24 (2H, s), 4.2-4.05 (2H, m), 3.14 (1H, m), 3.03 (3H, s), 2.95 (2H, m), 2.12˜2.04 (2H, m), 1.80 (2H, m), 1.46 (9H, s).

1. temperatureThe mixture was heated
2. temperatureunder reflux overnight
3. temperaturecooled
4. washthe mixture was washed successively with H2O and brine
5. dry with materialAfter drying (Na2SO4)
6. customthe solvent was removed
7. customThe residue was purified by flash chromatography on silica gel