反应详情

To a solution of crude ester 9 (10 g) in 200 mL of THF:water:methanol (150:25:25) was added with stirring 4.2 g Lithium hydroxide (3 eq). The atmosphere was replaced with nitrogen and the mixture was stirred for 5 h and then cooled via ice-water bath. The golden-brown mixture was slowly acidified with 2N aqueous hydrochloric acid to pH2. The partially precipitated acid was extracted in two portions with 4×250 mL of ethyl acetate. The combined organic layers were washed with 2×75 mL of water and 75 mL of brine, dried over sodium sulfate, and concentrated in vacuo. The dark brown solid was partially purified by suction filtration column chromatography on silica gel (0 to 30% ethyl acetate in heptane) to give a yellow solid. This solid was resuspended in heptane and cooled in an ice bath. The mixture was filtered to yield a fine tan-yellow powder (6.88 g, 72%).

1. temperaturecooled via ice-water bath
2. extractionThe partially precipitated acid was extracted in two portions with 4×250 mL of ethyl acetate
3. washThe combined organic layers were washed with 2×75 mL of water and 75 mL of brine
4. dry with materialdried over sodium sulfate
5. concentrationconcentrated in vacuo
6. filtrationThe dark brown solid was partially purified by suction filtration column chromatography on silica gel (0 to 30% ethyl acetate in heptane)
7. customto give a yellow solid
8. temperaturecooled in an ice bath
9. filtrationThe mixture was filtered