反应详情

Piperazine-2-carboxylic acid dihydrochloride (10.0 g, 49.2 mmol) was dissolved in H2O (125 mL) and 1,4-dioxane (200 mL), and the solution was brought to pH 11 with 50% NaOH in H2O. Benzyl chloroformate (14 mL, 98 mmol) was added while maintaining the pH at 11 with 50% NaOH in H2O. After 1 h, an additional portion of benzyl chloroformate (2 mL, 14 mmol) was added. After 30 min, the solution was extracted with Et2O (3×100 mL). The aqueous layer was brought to pH 2 with concentrated HCl and extracted with EtOAc (3×200 mL). The combined EtOAc extracts were dried over Na2SO4, filtered, and concentrated under reduced pressure to give 18.9 g (96%) of the desired product as a thick oil. The material was used without further purification. LC-MS: RT=9.250 min; [M+H]+=421.1.

1. waitAfter 30 min
2. extractionthe solution was extracted with Et2O (3×100 mL)
3. extractionextracted with EtOAc (3×200 mL)
4. dry with materialThe combined EtOAc extracts were dried over Na2SO4
5. filtrationfiltered
6. concentrationconcentrated under reduced pressure