反应详情

A solution of the product from step (b) (55.3 g) in methanol (250 ml) and 1N aqu. NaOH (500 ml) was stirred at room temperature for 1 hour. The methanol was evaporated in vacuo and the remaining aqueous solution adjusted to pH 4 (2N aqu. HCl), saturated with NaCl, and extracted with ethyl acetate (×3). The combined extracts were washed with water and brine, dried over MgSO4 and evaporated in vacuo to give a brown oil which was flash chromatographed through a silica column using ethyl acetate and then crystallised from ethyl acetate to give the desired product (51.7 g).

1. customThe methanol was evaporated in vacuo
2. extractionextracted with ethyl acetate (×3)
3. washThe combined extracts were washed with water and brine
4. dry with materialdried over MgSO4
5. customevaporated in vacuo
6. customto give a brown oil which
7. customchromatographed through a silica column
8. customcrystallised from ethyl acetate