反应详情

To a solution of Intermediate 16b (550 mg, 1.54 mmol) in aqueous NaOH solution (1M, 3.85 mL, 3.85 mmol) and EtOAc (5 mL) at RT, was added 2,2,2-trichloroethyl chloroformate (0.32 mL, 2.31 mmol) over 2 min, then the mixture stirred vigorously for 30 min. The aqueous layer was extracted with EtOAc (10 mL), then the combined organics washed with brine (10 mL), dried (MgSO4), filtered and concentrated in vacuo to leave a yellow-brown oil. FCC, using 0-30% EtOAc in cyclohexane, gave the title compound as a white foam (337 mg, 41%). LCMS (Method 3): Rt 4.81 min, m/z 531, 533 [MH+].

1. extractionThe aqueous layer was extracted with EtOAc (10 mL)
2. washthe combined organics washed with brine (10 mL)
3. dry with materialdried (MgSO4)
4. filtrationfiltered
5. concentrationconcentrated in vacuo
6. customto leave a yellow-brown oil