反应详情

1.6M n-butyllithium-hexane solution (28.9 ml, 46.2 mmole) was added dropwise to a solution of diisopropylamine (6.5 ml, 46.4 mmole) in tetrahydrofuran (50 ml) at -60° C. under an argon atmosphere, with stirring. 10 minutes later, a solution of caprolactone (5.0 g, 43.8 mmole) in tetrahydrofuran (10 ml) was added dropwise to the solution. After the reaction was allowed to proceed for 20 minutes under the same reaction conditions, a solution of methyl iodide (7.5 g, 52.8 mmole) in hexamethylphosphormaide (9.2 ml) was added gradually to the reaction solution, and stirring was continued for 1 hour after the dropwise addition while maintaining the reaction mixture at -40° to -45° C. Saturated aqueous ammonium chloride solution (20 ml) was added to the reaction solution to terminate the reaction, and water (100 ml) was added to the mixture, followed by extraction of the product with ethyl acetate. The organic layer was washed with water, dried and concentrated. The residue was chromatographed on a column of silica gel, and development with isopropyl ether yielded 2-methylcaprolactam (3.7 g, 66%) [NMR (δ value): 1.18 (3H, d, 6 Hz), 2.5-2.9 (1H,m), 4.18-4.34 (2H,m)].

1. customto proceed for 20 minutes under the same reaction conditions
2. stirringstirring
3. additionafter the dropwise addition
4. temperaturewhile maintaining the reaction mixture at -40° to -45° C
5. customto terminate
6. customthe reaction, and water (100 ml)
7. additionwas added to the mixture
8. extractionfollowed by extraction of the product with ethyl acetate
9. washThe organic layer was washed with water
10. customdried
11. concentrationconcentrated
12. customThe residue was chromatographed on a column of silica gel, and development with isopropyl ether