反应详情

To a solution of the ester (5 g, 12.16 mmole) of Step G, in dry tetrahydrofuran (66 mL) is added 1N-LiOH (37 mL, 37 mmole) and the mixture is stirred under nitrogen at room temperature for 2.5 hours (TLC, toluene-MeOH 9:1). The tetrahydrofuran is evaporated and the residue is diluted with water, acidified (to pH 6.5) with 10% acetic acid and extracted with ethyl acetate (3×). The extracts are washed with brine, dried (MgSO4) and evaporated to dryness. The crude product (4.94 g, pale yellow solid) is recrystallized from ethyl acetate to provide 3.65 g (75%) of the pure title compound (white solid, m.p. 146°-147° C.).

1. customThe tetrahydrofuran is evaporated
2. additionthe residue is diluted with water
3. extractionextracted with ethyl acetate (3×)
4. washThe extracts are washed with brine
5. dry with materialdried (MgSO4)
6. customevaporated to dryness
7. customThe crude product (4.94 g, pale yellow solid) is recrystallized from ethyl acetate