反应详情

A solution of sodium methoxide is generated by treating metallic sodium (29 g, 1.26 mol) with 1000 mL of anhydrous methanol by dropwise addition under an inert atmosphere. After the metal is completely consumed, the solution is heated at reflux temperature for 30 minutes and then cooled to room temperature. 2-Chloro-5-methyl-6-fluorobenzamide (42 g, 0.22 mol) is added and stirring continued for an additional 30 minutes at room temperature. N-Bromosuccinimide (78 g, 0.44 mol) is then slowly added via a powder additional funnel. The reaction mixture is warmed to 60° C. for 3 hours during which time foaming is observed. The reaction mixture is cooled to room temperature and most of the solvent is removed by rotary evaporator. The residue is partitioned between EtOAc (1000 mL) and water (1000 mL). The organic layer is separted and washed with water (500 mL) and then brine (2×500 mL). The organic layer is dried (MgSO4), filtered and concentrated by rotary evaporator the crude product is then purified using flash chromatography, eluting with 4:1 hexanes/EtOAc to give N-(2-chloro-5-methyl-6-fluorophenyl)-carbamic acid methyl ester as a white solid (m.p. 109–112° C.).

1. additionby dropwise addition under an inert atmosphere
2. customAfter the metal is completely consumed
3. temperaturethe solution is heated
4. temperatureat reflux temperature for 30 minutes
5. temperatureThe reaction mixture is warmed to 60° C. for 3 hours during which time foaming
6. temperatureThe reaction mixture is cooled to room temperature and most of the solvent
7. customis removed by rotary evaporator
8. customThe residue is partitioned between EtOAc (1000 mL) and water (1000 mL)
9. washwashed with water (500 mL)
10. dry with materialThe organic layer is dried (MgSO4)
11. filtrationfiltered
12. concentrationconcentrated by rotary evaporator the crude product
13. customis then purified
14. washeluting with 4:1 hexanes/EtOAc