反应详情

A solution of the ester (2.2 g, 4.3 mmol) of Step A in dioxane (20 mL) containing 1N NaOH (7 mL) is heated at reflux under nitrogen for 4 hrs. The solvent is removed and the residue is partitioned between dilute HCl and ether (30 mL each). The organic phase is washed with brine, dried (Na2SO4) and filtered. The filtrate is treated with tris(hydroxymethyl)aminomethane (0.485 g) in methanol (20 mL). The solvent is evaporated to a syrup in vacuo and diluted with ethyl acetate. The crystalline solid is collected (white solid, 1.6 g, 60%) and recrystallized from methanol-water to provide the pure title compound (0.89 g, m.p. 137°-138° C.).

1. temperatureis heated
2. temperatureat reflux under nitrogen for 4 hrs
3. customThe solvent is removed
4. customthe residue is partitioned between dilute HCl and ether (30 mL each)
5. washThe organic phase is washed with brine
6. dry with materialdried (Na2SO4)
7. filtrationfiltered
8. additionThe filtrate is treated with tris(hydroxymethyl)aminomethane (0.485 g) in methanol (20 mL)
9. customThe solvent is evaporated to a syrup in vacuo
10. additiondiluted with ethyl acetate
11. customThe crystalline solid is collected (white solid, 1.6 g, 60%)
12. customrecrystallized from methanol-water